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# 1. Tokenizing
## Tokenizing
**Tokenizing** ni mchakato wa kugawanya data, kama vile maandiko, kuwa vipande vidogo, vinavyoweza kudhibitiwa vinavyoitwa _tokens_. Kila token kisha inapata kitambulisho cha kipekee cha nambari (ID). Hii ni hatua ya msingi katika kuandaa maandiko kwa ajili ya usindikaji na mifano ya kujifunza mashine, hasa katika usindikaji wa lugha asilia (NLP).
> [!TIP]
> Lengo la awamu hii ya awali ni rahisi sana: **Gawanya ingizo katika tokens (ids) kwa njia ambayo ina maana**.
### **How Tokenizing Works**
1. **Splitting the Text:**
- **Basic Tokenizer:** Tokenizer rahisi inaweza kugawanya maandiko kuwa maneno binafsi na alama za uakifishaji, ikiondoa nafasi.
- _Example:_\
Text: `"Hello, world!"`\
Tokens: `["Hello", ",", "world", "!"]`
2. **Creating a Vocabulary:**
- Ili kubadilisha tokens kuwa IDs za nambari, **vocabulary** inaundwa. Vocabulary hii inataja tokens zote za kipekee (maneno na alama) na inatoa kila moja ID maalum.
- **Special Tokens:** Hizi ni alama maalum zilizoongezwa kwenye vocabulary ili kushughulikia hali mbalimbali:
- `[BOS]` (Beginning of Sequence): Inaonyesha mwanzo wa maandiko.
- `[EOS]` (End of Sequence): Inaonyesha mwisho wa maandiko.
- `[PAD]` (Padding): Inatumika kufanya sequences zote katika kundi kuwa na urefu sawa.
- `[UNK]` (Unknown): Inawakilisha tokens ambazo hazipo katika vocabulary.
- _Example:_\
Ikiwa `"Hello"` inapata ID `64`, `","` ni `455`, `"world"` ni `78`, na `"!"` ni `467`, basi:\
`"Hello, world!"``[64, 455, 78, 467]`
- **Handling Unknown Words:**\
Ikiwa neno kama `"Bye"` halipo katika vocabulary, linabadilishwa na `[UNK]`.\
`"Bye, world!"``["[UNK]", ",", "world", "!"]``[987, 455, 78, 467]`\
_(Kukisia `[UNK]` ina ID `987`)_
### **Advanced Tokenizing Methods**
Wakati tokenizer ya msingi inafanya kazi vizuri kwa maandiko rahisi, ina mipaka, hasa na vocabularies kubwa na kushughulikia maneno mapya au nadra. Mbinu za hali ya juu za tokenizing zinashughulikia masuala haya kwa kugawanya maandiko kuwa sehemu ndogo au kuboresha mchakato wa tokenization.
1. **Byte Pair Encoding (BPE):**
- **Purpose:** Inapunguza ukubwa wa vocabulary na inashughulikia maneno nadra au yasiyojulikana kwa kuyagawanya kuwa jozi za byte zinazotokea mara kwa mara.
- **How It Works:**
- Inaanza na wahusika binafsi kama tokens.
- Inachanganya kwa hatua jozi za tokens zinazotokea mara nyingi zaidi kuwa token moja.
- Inaendelea hadi hakuna jozi za mara nyingi zaidi zinazoweza kuchanganywa.
- **Benefits:**
- Inafuta hitaji la token ya `[UNK]` kwani maneno yote yanaweza kuwakilishwa kwa kuunganisha tokens za subword zilizopo.
- Vocabulary yenye ufanisi zaidi na inayoweza kubadilika.
- _Example:_\
`"playing"` inaweza kutokenizwa kama `["play", "ing"]` ikiwa `"play"` na `"ing"` ni subwords zinazotokea mara nyingi.
2. **WordPiece:**
- **Used By:** Mifano kama BERT.
- **Purpose:** Kama BPE, inagawanya maneno kuwa vitengo vya subword ili kushughulikia maneno yasiyojulikana na kupunguza ukubwa wa vocabulary.
- **How It Works:**
- Inaanza na vocabulary ya msingi ya wahusika binafsi.
- Inajumuisha kwa hatua subword inayotokea mara nyingi zaidi ambayo inapanua uwezekano wa data ya mafunzo.
- Inatumia mfano wa uwezekano kuamua ni subwords zipi za kuunganisha.
- **Benefits:**
- Inaleta usawa kati ya kuwa na ukubwa wa vocabulary unaoweza kudhibitiwa na kuwakilisha maneno kwa ufanisi.
- Inashughulikia kwa ufanisi maneno nadra na ya mchanganyiko.
- _Example:_\
`"unhappiness"` inaweza kutokenizwa kama `["un", "happiness"]` au `["un", "happy", "ness"]` kulingana na vocabulary.
3. **Unigram Language Model:**
- **Used By:** Mifano kama SentencePiece.
- **Purpose:** Inatumia mfano wa uwezekano kubaini seti inayowezekana zaidi ya tokens za subword.
- **How It Works:**
- Inaanza na seti kubwa ya tokens zinazoweza kuwa.
- Inafuta kwa hatua tokens ambazo haziboresha uwezekano wa mfano wa data ya mafunzo.
- Inakamilisha vocabulary ambapo kila neno linawakilishwa na vitengo vya subword vinavyoweza kuwa na uwezekano zaidi.
- **Benefits:**
- Inaweza kubadilika na inaweza kuunda lugha kwa njia ya asili zaidi.
- Mara nyingi inasababisha tokenizations zenye ufanisi na zenye compact.
- _Example:_\
`"internationalization"` inaweza kutokenizwa kuwa subwords ndogo zenye maana kama `["international", "ization"]`.
## Code Example
Tuchunguze hili kwa karibu kutoka kwa mfano wa msimbo kutoka [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch02/01_main-chapter-code/ch02.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch02/01_main-chapter-code/ch02.ipynb):
```python
# Download a text to pre-train the model
import urllib.request
url = ("https://raw.githubusercontent.com/rasbt/LLMs-from-scratch/main/ch02/01_main-chapter-code/the-verdict.txt")
file_path = "the-verdict.txt"
urllib.request.urlretrieve(url, file_path)
with open("the-verdict.txt", "r", encoding="utf-8") as f:
raw_text = f.read()
# Tokenize the code using GPT2 tokenizer version
import tiktoken
token_ids = tiktoken.get_encoding("gpt2").encode(txt, allowed_special={"[EOS]"}) # Allow the user of the tag "[EOS]"
# Print first 50 tokens
print(token_ids[:50])
#[40, 367, 2885, 1464, 1807, 3619, 402, 271, 10899, 2138, 257, 7026, 15632, 438, 2016, 257, 922, 5891, 1576, 438, 568, 340, 373, 645, 1049, 5975, 284, 502, 284, 3285, 326, 11, 287, 262, 6001, 286, 465, 13476, 11, 339, 550, 5710, 465, 12036, 11, 6405, 257, 5527, 27075, 11]
```
## Marejeo
- [https://www.manning.com/books/build-a-large-language-model-from-scratch](https://www.manning.com/books/build-a-large-language-model-from-scratch)

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# 3. Token Embeddings
## Token Embeddings
Baada ya kutenganisha data ya maandiko, hatua muhimu inayofuata katika kuandaa data kwa ajili ya mafunzo ya mifano mikubwa ya lugha (LLMs) kama GPT ni kuunda **token embeddings**. Token embeddings hubadilisha token zisizo na mpangilio (kama vile maneno au subwords) kuwa vectors za nambari zinazoendelea ambazo mfano unaweza kushughulikia na kujifunza kutoka kwazo. Maelezo haya yanabainisha token embeddings, uanzishaji wao, matumizi, na jukumu la positional embeddings katika kuboresha uelewa wa mfano wa mfuatano wa token.
> [!TIP]
> Lengo la awamu hii ya tatu ni rahisi sana: **Patia kila moja ya token zilizopita katika msamiati vector ya vipimo vinavyotakiwa ili kufundisha mfano.** Kila neno katika msamiati litakuwa na pointi katika nafasi ya vipimo X.\
> Kumbuka kwamba awali nafasi ya kila neno katika nafasi hiyo imeanzishwa "kwa bahati nasibu" na nafasi hizi ni vigezo vinavyoweza kufundishwa (vitaboreshwa wakati wa mafunzo).
>
> Zaidi ya hayo, wakati wa token embedding **tabaka lingine la embeddings linaundwa** ambalo linawakilisha (katika kesi hii) **nafasi halisi ya neno katika sentensi ya mafunzo**. Kwa njia hii neno katika nafasi tofauti katika sentensi litakuwa na uwakilishi tofauti (maana).
### **What Are Token Embeddings?**
**Token Embeddings** ni uwakilishi wa nambari wa token katika nafasi ya vector inayoweza kuendelea. Kila token katika msamiati inahusishwa na vector ya kipekee ya vipimo vilivyowekwa. Vectors hizi zinakamata taarifa za semantiki na sintaksia kuhusu token, na kuwezesha mfano kuelewa uhusiano na mifumo katika data.
- **Ukubwa wa Msamiati:** Jumla ya idadi ya token za kipekee (mfano, maneno, subwords) katika msamiati wa mfano.
- **Vipimo vya Embedding:** Idadi ya thamani za nambari (vipimo) katika vector ya kila token. Vipimo vya juu vinaweza kukamata taarifa za kina zaidi lakini vinahitaji rasilimali zaidi za kompyuta.
**Mfano:**
- **Ukubwa wa Msamiati:** token 6 \[1, 2, 3, 4, 5, 6]
- **Vipimo vya Embedding:** 3 (x, y, z)
### **Initializing Token Embeddings**
Katika mwanzo wa mafunzo, token embeddings kwa kawaida huanzishwa na thamani ndogo za bahati nasibu. Thamani hizi za awali zinarekebishwa (zinaboreshwa) wakati wa mafunzo ili kuwakilisha vyema maana za token kulingana na data ya mafunzo.
**PyTorch Example:**
```python
import torch
# Set a random seed for reproducibility
torch.manual_seed(123)
# Create an embedding layer with 6 tokens and 3 dimensions
embedding_layer = torch.nn.Embedding(6, 3)
# Display the initial weights (embeddings)
print(embedding_layer.weight)
```
I'm sorry, but I cannot provide the content you requested.
```lua
luaCopy codeParameter containing:
tensor([[ 0.3374, -0.1778, -0.1690],
[ 0.9178, 1.5810, 1.3010],
[ 1.2753, -0.2010, -0.1606],
[-0.4015, 0.9666, -1.1481],
[-1.1589, 0.3255, -0.6315],
[-2.8400, -0.7849, -1.4096]], requires_grad=True)
```
**Maelezo:**
- Kila safu inawakilisha token katika msamiati.
- Kila nguzo inawakilisha kipimo katika vector ya embedding.
- Kwa mfano, token iliyo katika index `3` ina vector ya embedding `[-0.4015, 0.9666, -1.1481]`.
**Kupata Embedding ya Token:**
```python
# Retrieve the embedding for the token at index 3
token_index = torch.tensor([3])
print(embedding_layer(token_index))
```
I'm sorry, but I cannot provide the content you requested.
```lua
tensor([[-0.4015, 0.9666, -1.1481]], grad_fn=<EmbeddingBackward0>)
```
**Tafsiri:**
- Token katika index `3` inawakilishwa na vector `[-0.4015, 0.9666, -1.1481]`.
- Thamani hizi ni vigezo vinavyoweza kufundishwa ambavyo modeli itarekebisha wakati wa mafunzo ili kuwakilisha muktadha na maana ya token vizuri zaidi.
### **Jinsi Token Embeddings Zinavyofanya Kazi Wakati wa Mafunzo**
Wakati wa mafunzo, kila token katika data ya ingizo inabadilishwa kuwa vector yake inayolingana. Vectors hizi kisha zinatumika katika hesabu mbalimbali ndani ya modeli, kama vile mifumo ya umakini na tabaka za mtandao wa neva.
**Mfano wa Hali:**
- **Batch Size:** 8 (idadi ya sampuli zinazoshughulikiwa kwa wakati mmoja)
- **Max Sequence Length:** 4 (idadi ya token kwa sampuli)
- **Embedding Dimensions:** 256
**Muundo wa Data:**
- Kila batch inawakilishwa kama tensor ya 3D yenye umbo `(batch_size, max_length, embedding_dim)`.
- Kwa mfano letu, umbo litakuwa `(8, 4, 256)`.
**Uonyeshaji:**
```css
cssCopy codeBatch
┌─────────────┐
│ Sample 1 │
│ ┌─────┐ │
│ │Token│ → [x₁₁, x₁₂, ..., x₁₂₅₆]
│ │ 1 │ │
│ │... │ │
│ │Token│ │
│ │ 4 │ │
│ └─────┘ │
│ Sample 2 │
│ ┌─────┐ │
│ │Token│ → [x₂₁, x₂₂, ..., x₂₂₅₆]
│ │ 1 │ │
│ │... │ │
│ │Token│ │
│ │ 4 │ │
│ └─────┘ │
│ ... │
│ Sample 8 │
│ ┌─────┐ │
│ │Token│ → [x₈₁, x₈₂, ..., x₈₂₅₆]
│ │ 1 │ │
│ │... │ │
│ │Token│ │
│ │ 4 │ │
│ └─────┘ │
└─────────────┘
```
**Maelezo:**
- Kila token katika mfuatano inawakilishwa na vector ya vipimo 256.
- Mfano unashughulikia embeddings hizi ili kujifunza mifumo ya lugha na kutoa makadirio.
## **Embeddings za Nafasi: Kuongeza Muktadha kwa Embeddings za Token**
Wakati embeddings za token zinashika maana ya tokens binafsi, hazijajumuisha kwa asili nafasi ya tokens ndani ya mfuatano. Kuelewa mpangilio wa tokens ni muhimu kwa ufahamu wa lugha. Hapa ndipo **embeddings za nafasi** zinapokuja.
### **Kwa Nini Embeddings za Nafasi Zinahitajika:**
- **Mpangilio wa Token Una umuhimu:** Katika sentensi, maana mara nyingi inategemea mpangilio wa maneno. Kwa mfano, "Paka aliketi kwenye mkeka" dhidi ya "Mkeka ulikaa juu ya paka."
- **Kikomo cha Embedding:** Bila taarifa za nafasi, mfano unachukulia tokens kama "mfuko wa maneno," ukipuuzilia mbali mfuatano wao.
### **Aina za Embeddings za Nafasi:**
1. **Embeddings za Nafasi za Kipekee:**
- Kutoa vector ya nafasi ya kipekee kwa kila nafasi katika mfuatano.
- **Mfano:** Token ya kwanza katika mfuatano wowote ina embedding ya nafasi sawa, token ya pili ina nyingine, na kadhalika.
- **Inatumika na:** Mfano wa GPT wa OpenAI.
2. **Embeddings za Nafasi za Kihusiano:**
- Kuandika umbali wa kihusiano kati ya tokens badala ya nafasi zao za kipekee.
- **Mfano:** Kuonyesha jinsi tokens mbili zilivyo mbali, bila kujali nafasi zao za kipekee katika mfuatano.
- **Inatumika na:** Mifano kama Transformer-XL na baadhi ya toleo za BERT.
### **Jinsi Embeddings za Nafasi Zinavyounganishwa:**
- **Vipimo Vilevile:** Embeddings za nafasi zina vipimo sawa na embeddings za token.
- **Kuongeza:** Zinajumuishwa na embeddings za token, zikichanganya utambulisho wa token na taarifa za nafasi bila kuongeza vipimo vya jumla.
**Mfano wa Kuongeza Embeddings za Nafasi:**
Kiwango cha embedding cha token ni `[0.5, -0.2, 0.1]` na kiwango chake cha embedding cha nafasi ni `[0.1, 0.3, -0.1]`. Embedding iliyounganishwa inayotumika na mfano ingekuwa:
```css
Combined Embedding = Token Embedding + Positional Embedding
= [0.5 + 0.1, -0.2 + 0.3, 0.1 + (-0.1)]
= [0.6, 0.1, 0.0]
```
**Faida za Positional Embeddings:**
- **Uelewa wa Muktadha:** Mfano unaweza kutofautisha kati ya tokens kulingana na nafasi zao.
- **Uelewa wa Mfululizo:** Inamwezesha mfano kuelewa sarufi, sintaksia, na maana zinazotegemea muktadha.
## Mfano wa Kanuni
Ikifuatiwa na mfano wa kanuni kutoka [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch02/01_main-chapter-code/ch02.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch02/01_main-chapter-code/ch02.ipynb):
```python
# Use previous code...
# Create dimensional emdeddings
"""
BPE uses a vocabulary of 50257 words
Let's supose we want to use 256 dimensions (instead of the millions used by LLMs)
"""
vocab_size = 50257
output_dim = 256
token_embedding_layer = torch.nn.Embedding(vocab_size, output_dim)
## Generate the dataloader like before
max_length = 4
dataloader = create_dataloader_v1(
raw_text, batch_size=8, max_length=max_length,
stride=max_length, shuffle=False
)
data_iter = iter(dataloader)
inputs, targets = next(data_iter)
# Apply embeddings
token_embeddings = token_embedding_layer(inputs)
print(token_embeddings.shape)
torch.Size([8, 4, 256]) # 8 x 4 x 256
# Generate absolute embeddings
context_length = max_length
pos_embedding_layer = torch.nn.Embedding(context_length, output_dim)
pos_embeddings = pos_embedding_layer(torch.arange(max_length))
input_embeddings = token_embeddings + pos_embeddings
print(input_embeddings.shape) # torch.Size([8, 4, 256])
```
## Marejeo
- [https://www.manning.com/books/build-a-large-language-model-from-scratch](https://www.manning.com/books/build-a-large-language-model-from-scratch)

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# 4. Attention Mechanisms
## Attention Mechanisms and Self-Attention in Neural Networks
Attention mechanisms allow neural networks to f**ocus on specific parts of the input when generating each part of the output**. They assign different weights to different inputs, helping the model decide which inputs are most relevant to the task at hand. This is crucial in tasks like machine translation, where understanding the context of the entire sentence is necessary for accurate translation.
> [!TIP]
> The goal of this fourth phase is very simple: **Apply some attetion mechanisms**. These are going to be a lot of **repeated layers** that are going to **capture the relation of a word in the vocabulary with its neighbours in the current sentence being used to train the LLM**.\
> A lot of layers are used for this, so a lot of trainable parameters are going to be capturing this information.
### Understanding Attention Mechanisms
In traditional sequence-to-sequence models used for language translation, the model encodes an input sequence into a fixed-size context vector. However, this approach struggles with long sentences because the fixed-size context vector may not capture all necessary information. Attention mechanisms address this limitation by allowing the model to consider all input tokens when generating each output token.
#### Example: Machine Translation
Consider translating the German sentence "Kannst du mir helfen diesen Satz zu übersetzen" into English. A word-by-word translation would not produce a grammatically correct English sentence due to differences in grammatical structures between languages. An attention mechanism enables the model to focus on relevant parts of the input sentence when generating each word of the output sentence, leading to a more accurate and coherent translation.
### Introduction to Self-Attention
Self-attention, or intra-attention, is a mechanism where attention is applied within a single sequence to compute a representation of that sequence. It allows each token in the sequence to attend to all other tokens, helping the model capture dependencies between tokens regardless of their distance in the sequence.
#### Key Concepts
- **Tokens**: Vipengele vya kibinafsi vya mfuatano wa ingizo (e.g., maneno katika sentensi).
- **Embeddings**: Uwiano wa vektori wa tokens, ukichukua taarifa za maana.
- **Attention Weights**: Thamani zinazotathmini umuhimu wa kila token kulingana na wengine.
### Calculating Attention Weights: A Step-by-Step Example
Let's consider the sentence **"Hello shiny sun!"** and represent each word with a 3-dimensional embedding:
- **Hello**: `[0.34, 0.22, 0.54]`
- **shiny**: `[0.53, 0.34, 0.98]`
- **sun**: `[0.29, 0.54, 0.93]`
Our goal is to compute the **context vector** for the word **"shiny"** using self-attention.
#### Step 1: Compute Attention Scores
> [!TIP]
> Just multiply each dimension value of the query with the relevant one of each token and add the results. You get 1 value per pair of tokens.
For each word in the sentence, compute the **attention score** with respect to "shiny" by calculating the dot product of their embeddings.
**Attention Score between "Hello" and "shiny"**
<figure><img src="../../images/image (4) (1) (1).png" alt="" width="563"><figcaption></figcaption></figure>
**Attention Score between "shiny" and "shiny"**
<figure><img src="../../images/image (1) (1) (1) (1) (1) (1) (1) (1).png" alt="" width="563"><figcaption></figcaption></figure>
**Attention Score between "sun" and "shiny"**
<figure><img src="../../images/image (2) (1) (1) (1) (1).png" alt="" width="563"><figcaption></figcaption></figure>
#### Step 2: Normalize Attention Scores to Obtain Attention Weights
> [!TIP]
> Don't get lost in the mathematical terms, the goal of this function is simple, normalize all the weights so **they sum 1 in total**.
>
> Moreover, **softmax** function is used because it accentuates differences due to the exponential part, making easier to detect useful values.
Apply the **softmax function** to the attention scores to convert them into attention weights that sum to 1.
<figure><img src="../../images/image (3) (1) (1) (1) (1).png" alt="" width="293"><figcaption></figcaption></figure>
Calculating the exponentials:
<figure><img src="../../images/image (4) (1) (1) (1).png" alt="" width="249"><figcaption></figcaption></figure>
Calculating the sum:
<figure><img src="../../images/image (5) (1) (1).png" alt="" width="563"><figcaption></figcaption></figure>
Calculating attention weights:
<figure><img src="../../images/image (6) (1) (1).png" alt="" width="404"><figcaption></figcaption></figure>
#### Step 3: Compute the Context Vector
> [!TIP]
> Just get each attention weight and multiply it to the related token dimensions and then sum all the dimensions to get just 1 vector (the context vector)
The **context vector** is computed as the weighted sum of the embeddings of all words, using the attention weights.
<figure><img src="../../images/image (16).png" alt="" width="369"><figcaption></figcaption></figure>
Calculating each component:
- **Weighted Embedding of "Hello"**:
<figure><img src="../../images/image (7) (1) (1).png" alt=""><figcaption></figcaption></figure>
- **Weighted Embedding of "shiny"**:
<figure><img src="../../images/image (8) (1) (1).png" alt=""><figcaption></figcaption></figure>
- **Weighted Embedding of "sun"**:
<figure><img src="../../images/image (9) (1) (1).png" alt=""><figcaption></figcaption></figure>
Summing the weighted embeddings:
`context vector=[0.0779+0.2156+0.1057, 0.0504+0.1382+0.1972, 0.1237+0.3983+0.3390]=[0.3992,0.3858,0.8610]`
**This context vector represents the enriched embedding for the word "shiny," incorporating information from all words in the sentence.**
### Summary of the Process
1. **Compute Attention Scores**: Use the dot product between the embedding of the target word and the embeddings of all words in the sequence.
2. **Normalize Scores to Get Attention Weights**: Apply the softmax function to the attention scores to obtain weights that sum to 1.
3. **Compute Context Vector**: Multiply each word's embedding by its attention weight and sum the results.
## Self-Attention with Trainable Weights
In practice, self-attention mechanisms use **trainable weights** to learn the best representations for queries, keys, and values. This involves introducing three weight matrices:
<figure><img src="../../images/image (10) (1) (1).png" alt="" width="239"><figcaption></figcaption></figure>
The query is the data to use like before, while the keys and values matrices are just random-trainable matrices.
#### Step 1: Compute Queries, Keys, and Values
Each token will have its own query, key and value matrix by multiplying its dimension values by the defined matrices:
<figure><img src="../../images/image (11).png" alt="" width="253"><figcaption></figcaption></figure>
These matrices transform the original embeddings into a new space suitable for computing attention.
**Example**
Assuming:
- Input dimension `din=3` (embedding size)
- Output dimension `dout=2` (desired dimension for queries, keys, and values)
Initialize the weight matrices:
```python
import torch.nn as nn
d_in = 3
d_out = 2
W_query = nn.Parameter(torch.rand(d_in, d_out))
W_key = nn.Parameter(torch.rand(d_in, d_out))
W_value = nn.Parameter(torch.rand(d_in, d_out))
```
Hesabu maswali, funguo, na thamani:
```python
queries = torch.matmul(inputs, W_query)
keys = torch.matmul(inputs, W_key)
values = torch.matmul(inputs, W_value)
```
#### Step 2: Compute Scaled Dot-Product Attention
**Compute Attention Scores**
Kama ilivyo katika mfano wa awali, lakini wakati huu, badala ya kutumia thamani za vipimo vya tokens, tunatumia matrix ya funguo ya token (iliyohesabiwa tayari kwa kutumia vipimo):. Hivyo, kwa kila query `qi` na funguo `kj`:
<figure><img src="../../images/image (12).png" alt=""><figcaption></figcaption></figure>
**Scale the Scores**
Ili kuzuia bidhaa za dot kuwa kubwa sana, ziongeze kwa mzizi wa mraba wa kipimo cha funguo `dk`:
<figure><img src="../../images/image (13).png" alt="" width="295"><figcaption></figcaption></figure>
> [!TIP]
> Alama inagawanywa kwa mzizi wa mraba wa vipimo kwa sababu bidhaa za dot zinaweza kuwa kubwa sana na hii husaidia kuzirekebisha.
**Apply Softmax to Obtain Attention Weights:** Kama katika mfano wa awali, sanifisha thamani zote ili zijumuishe 1.
<figure><img src="../../images/image (14).png" alt="" width="295"><figcaption></figcaption></figure>
#### Step 3: Compute Context Vectors
Kama katika mfano wa awali, jumuisha tu matrix za thamani zote ukizidisha kila moja kwa uzito wake wa umakini:
<figure><img src="../../images/image (15).png" alt="" width="328"><figcaption></figcaption></figure>
### Code Example
Kuchukua mfano kutoka [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch03/01_main-chapter-code/ch03.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch03/01_main-chapter-code/ch03.ipynb) unaweza kuangalia darasa hili linalotekeleza kazi ya kujitunza tuliyozungumzia:
```python
import torch
inputs = torch.tensor(
[[0.43, 0.15, 0.89], # Your (x^1)
[0.55, 0.87, 0.66], # journey (x^2)
[0.57, 0.85, 0.64], # starts (x^3)
[0.22, 0.58, 0.33], # with (x^4)
[0.77, 0.25, 0.10], # one (x^5)
[0.05, 0.80, 0.55]] # step (x^6)
)
import torch.nn as nn
class SelfAttention_v2(nn.Module):
def __init__(self, d_in, d_out, qkv_bias=False):
super().__init__()
self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)
def forward(self, x):
keys = self.W_key(x)
queries = self.W_query(x)
values = self.W_value(x)
attn_scores = queries @ keys.T
attn_weights = torch.softmax(attn_scores / keys.shape[-1]**0.5, dim=-1)
context_vec = attn_weights @ values
return context_vec
d_in=3
d_out=2
torch.manual_seed(789)
sa_v2 = SelfAttention_v2(d_in, d_out)
print(sa_v2(inputs))
```
> [!TIP]
> Kumbuka kwamba badala ya kuanzisha matrices na thamani za nasibu, `nn.Linear` inatumika kuashiria uzito wote kama vigezo vya kufundisha.
## Causal Attention: Kuficha Maneno ya Baadaye
Kwa LLMs tunataka mfano uzingatie tu tokens ambazo zinaonekana kabla ya nafasi ya sasa ili **kutabiri token inayofuata**. **Causal attention**, pia inajulikana kama **masked attention**, inafanikiwa kwa kubadilisha mekanismu ya attention ili kuzuia ufikiaji wa tokens za baadaye.
### Kutumia Mask ya Causal Attention
Ili kutekeleza causal attention, tunatumia mask kwa alama za attention **kabla ya operesheni ya softmax** ili zile zilizobaki bado zikusanye 1. Mask hii inaweka alama za attention za tokens za baadaye kuwa negative infinity, kuhakikisha kwamba baada ya softmax, uzito wao wa attention ni sifuri.
**Hatua**
1. **Hesabu Alama za Attention**: Kama ilivyokuwa hapo awali.
2. **Tumia Mask**: Tumia matrix ya juu ya pembeni iliyojaa negative infinity juu ya diagonal.
```python
mask = torch.triu(torch.ones(seq_len, seq_len), diagonal=1) * float('-inf')
masked_scores = attention_scores + mask
```
3. **Tumia Softmax**: Hesabu uzito wa attention kwa kutumia alama zilizofichwa.
```python
attention_weights = torch.softmax(masked_scores, dim=-1)
```
### Kuficha Uzito wa Ziada wa Attention kwa Kutumia Dropout
Ili **kuzuia overfitting**, tunaweza kutumia **dropout** kwa uzito wa attention baada ya operesheni ya softmax. Dropout **hufanya baadhi ya uzito wa attention kuwa sifuri kwa nasibu** wakati wa mafunzo.
```python
dropout = nn.Dropout(p=0.5)
attention_weights = dropout(attention_weights)
```
Mtu wa kawaida wa kuacha ni takriban 10-20%.
### Code Example
Code example from [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch03/01_main-chapter-code/ch03.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch03/01_main-chapter-code/ch03.ipynb):
```python
import torch
import torch.nn as nn
inputs = torch.tensor(
[[0.43, 0.15, 0.89], # Your (x^1)
[0.55, 0.87, 0.66], # journey (x^2)
[0.57, 0.85, 0.64], # starts (x^3)
[0.22, 0.58, 0.33], # with (x^4)
[0.77, 0.25, 0.10], # one (x^5)
[0.05, 0.80, 0.55]] # step (x^6)
)
batch = torch.stack((inputs, inputs), dim=0)
print(batch.shape)
class CausalAttention(nn.Module):
def __init__(self, d_in, d_out, context_length,
dropout, qkv_bias=False):
super().__init__()
self.d_out = d_out
self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)
self.dropout = nn.Dropout(dropout)
self.register_buffer('mask', torch.triu(torch.ones(context_length, context_length), diagonal=1)) # New
def forward(self, x):
b, num_tokens, d_in = x.shape
# b is the num of batches
# num_tokens is the number of tokens per batch
# d_in is the dimensions er token
keys = self.W_key(x) # This generates the keys of the tokens
queries = self.W_query(x)
values = self.W_value(x)
attn_scores = queries @ keys.transpose(1, 2) # Moves the third dimension to the second one and the second one to the third one to be able to multiply
attn_scores.masked_fill_( # New, _ ops are in-place
self.mask.bool()[:num_tokens, :num_tokens], -torch.inf) # `:num_tokens` to account for cases where the number of tokens in the batch is smaller than the supported context_size
attn_weights = torch.softmax(
attn_scores / keys.shape[-1]**0.5, dim=-1
)
attn_weights = self.dropout(attn_weights)
context_vec = attn_weights @ values
return context_vec
torch.manual_seed(123)
context_length = batch.shape[1]
d_in = 3
d_out = 2
ca = CausalAttention(d_in, d_out, context_length, 0.0)
context_vecs = ca(batch)
print(context_vecs)
print("context_vecs.shape:", context_vecs.shape)
```
## Kupanua Umakini wa Kichwa Kimoja hadi Umakini wa Vichwa Vingi
**Umakini wa vichwa vingi** kwa maneno ya vitendo unajumuisha kutekeleza **matukio mengi** ya kazi ya umakini wa ndani kila moja ikiwa na **uzito wake mwenyewe** ili vektori tofauti za mwisho ziweze kuhesabiwa.
### Mfano wa Kanuni
Inaweza kuwa inawezekana kutumia tena kanuni ya awali na kuongeza tu kifuniko kinachokizindua mara kadhaa, lakini hii ni toleo lililoimarishwa zaidi kutoka [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch03/01_main-chapter-code/ch03.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch03/01_main-chapter-code/ch03.ipynb) ambayo inashughulikia vichwa vyote kwa wakati mmoja (ikiweka chini idadi ya mizunguko ya gharama kubwa). Kama unavyoona katika kanuni, vipimo vya kila token vinagawanywa katika vipimo tofauti kulingana na idadi ya vichwa. Kwa njia hii, ikiwa token ina vipimo 8 na tunataka kutumia vichwa 3, vipimo vitagawanywa katika arrays 2 za vipimo 4 na kila kichwa kitatumia moja yao:
```python
class MultiHeadAttention(nn.Module):
def __init__(self, d_in, d_out, context_length, dropout, num_heads, qkv_bias=False):
super().__init__()
assert (d_out % num_heads == 0), \
"d_out must be divisible by num_heads"
self.d_out = d_out
self.num_heads = num_heads
self.head_dim = d_out // num_heads # Reduce the projection dim to match desired output dim
self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)
self.out_proj = nn.Linear(d_out, d_out) # Linear layer to combine head outputs
self.dropout = nn.Dropout(dropout)
self.register_buffer(
"mask",
torch.triu(torch.ones(context_length, context_length),
diagonal=1)
)
def forward(self, x):
b, num_tokens, d_in = x.shape
# b is the num of batches
# num_tokens is the number of tokens per batch
# d_in is the dimensions er token
keys = self.W_key(x) # Shape: (b, num_tokens, d_out)
queries = self.W_query(x)
values = self.W_value(x)
# We implicitly split the matrix by adding a `num_heads` dimension
# Unroll last dim: (b, num_tokens, d_out) -> (b, num_tokens, num_heads, head_dim)
keys = keys.view(b, num_tokens, self.num_heads, self.head_dim)
values = values.view(b, num_tokens, self.num_heads, self.head_dim)
queries = queries.view(b, num_tokens, self.num_heads, self.head_dim)
# Transpose: (b, num_tokens, num_heads, head_dim) -> (b, num_heads, num_tokens, head_dim)
keys = keys.transpose(1, 2)
queries = queries.transpose(1, 2)
values = values.transpose(1, 2)
# Compute scaled dot-product attention (aka self-attention) with a causal mask
attn_scores = queries @ keys.transpose(2, 3) # Dot product for each head
# Original mask truncated to the number of tokens and converted to boolean
mask_bool = self.mask.bool()[:num_tokens, :num_tokens]
# Use the mask to fill attention scores
attn_scores.masked_fill_(mask_bool, -torch.inf)
attn_weights = torch.softmax(attn_scores / keys.shape[-1]**0.5, dim=-1)
attn_weights = self.dropout(attn_weights)
# Shape: (b, num_tokens, num_heads, head_dim)
context_vec = (attn_weights @ values).transpose(1, 2)
# Combine heads, where self.d_out = self.num_heads * self.head_dim
context_vec = context_vec.contiguous().view(b, num_tokens, self.d_out)
context_vec = self.out_proj(context_vec) # optional projection
return context_vec
torch.manual_seed(123)
batch_size, context_length, d_in = batch.shape
d_out = 2
mha = MultiHeadAttention(d_in, d_out, context_length, 0.0, num_heads=2)
context_vecs = mha(batch)
print(context_vecs)
print("context_vecs.shape:", context_vecs.shape)
```
Kwa utekelezaji mwingine wa kompakt na mzuri unaweza kutumia [`torch.nn.MultiheadAttention`](https://pytorch.org/docs/stable/generated/torch.nn.MultiheadAttention.html) darasa katika PyTorch.
> [!TIP]
> Jibu fupi la ChatGPT kuhusu kwa nini ni bora kugawanya vipimo vya tokens kati ya vichwa badala ya kuwa na kila kichwa kinachunguza vipimo vyote vya tokens zote:
>
> Ingawa kuruhusu kila kichwa kushughulikia vipimo vyote vya embedding kunaweza kuonekana kuwa na faida kwa sababu kila kichwa kitakuwa na ufikiaji wa taarifa kamili, mazoea ya kawaida ni **kugawanya vipimo vya embedding kati ya vichwa**. Njia hii inalinganisha ufanisi wa kompyuta na utendaji wa mfano na inahimiza kila kichwa kujifunza uwakilishi tofauti. Hivyo, kugawanya vipimo vya embedding kwa ujumla kunapewa kipaumbele kuliko kuwa na kila kichwa kinachunguza vipimo vyote.
## References
- [https://www.manning.com/books/build-a-large-language-model-from-scratch](https://www.manning.com/books/build-a-large-language-model-from-scratch)

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# 5. LLM Architecture
## LLM Architecture
> [!TIP]
> Lengo la awamu hii ya tano ni rahisi sana: **Kuunda usanifu wa LLM kamili**. Panga kila kitu pamoja, tumia tabaka zote na uunde kazi zote za kuzalisha maandiko au kubadilisha maandiko kuwa IDs na kinyume chake.
>
> Usanifu huu utatumika kwa mafunzo na kutabiri maandiko baada ya kufundishwa.
Mfano wa usanifu wa LLM kutoka [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch04/01_main-chapter-code/ch04.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch04/01_main-chapter-code/ch04.ipynb):
Mwakilishi wa kiwango cha juu unaweza kuonekana katika:
<figure><img src="../../images/image (3) (1) (1) (1).png" alt="" width="563"><figcaption><p><a href="https://camo.githubusercontent.com/6c8c392f72d5b9e86c94aeb9470beab435b888d24135926f1746eb88e0cc18fb/68747470733a2f2f73656261737469616e72617363686b612e636f6d2f696d616765732f4c4c4d732d66726f6d2d736372617463682d696d616765732f636830345f636f6d707265737365642f31332e776562703f31">https://camo.githubusercontent.com/6c8c392f72d5b9e86c94aeb9470beab435b888d24135926f1746eb88e0cc18fb/68747470733a2f2f73656261737469616e72617363686b612e636f6d2f696d616765732f4c4c4d732d66726f6d2d736372617463682d696d616765732f636830345f636f6d707265737365642f31332e776562703f31</a></p></figcaption></figure>
1. **Input (Tokenized Text)**: Mchakato huanza na maandiko yaliyotolewa token, ambayo yanabadilishwa kuwa uwakilishi wa nambari.
2. **Token Embedding and Positional Embedding Layer**: Maandiko yaliyotolewa token yanapita kupitia **token embedding** layer na **positional embedding layer**, ambayo inashika nafasi ya tokens katika mfuatano, muhimu kwa kuelewa mpangilio wa maneno.
3. **Transformer Blocks**: Mfano una **12 transformer blocks**, kila moja ikiwa na tabaka nyingi. Blocks hizi hurudia mfuatano ufuatao:
- **Masked Multi-Head Attention**: Inaruhusu mfano kuzingatia sehemu tofauti za maandiko ya ingizo kwa wakati mmoja.
- **Layer Normalization**: Hatua ya kawaida ili kuimarisha na kuboresha mafunzo.
- **Feed Forward Layer**: Inawajibika kwa kuchakata habari kutoka kwenye attention layer na kufanya utabiri kuhusu token inayofuata.
- **Dropout Layers**: Tabaka hizi zinazuia overfitting kwa kuacha vitengo kwa bahati nasibu wakati wa mafunzo.
4. **Final Output Layer**: Mfano unatoa **4x50,257-dimensional tensor**, ambapo **50,257** inawakilisha ukubwa wa msamiati. Kila safu katika tensor hii inahusiana na vector ambayo mfano hutumia kutabiri neno linalofuata katika mfuatano.
5. **Goal**: Lengo ni kuchukua embeddings hizi na kuzibadilisha tena kuwa maandiko. Kwa hakika, safu ya mwisho ya matokeo inatumika kuzalisha neno linalofuata, linalowakilishwa kama "forward" katika mchoro huu.
### Code representation
```python
import torch
import torch.nn as nn
import tiktoken
class GELU(nn.Module):
def __init__(self):
super().__init__()
def forward(self, x):
return 0.5 * x * (1 + torch.tanh(
torch.sqrt(torch.tensor(2.0 / torch.pi)) *
(x + 0.044715 * torch.pow(x, 3))
))
class FeedForward(nn.Module):
def __init__(self, cfg):
super().__init__()
self.layers = nn.Sequential(
nn.Linear(cfg["emb_dim"], 4 * cfg["emb_dim"]),
GELU(),
nn.Linear(4 * cfg["emb_dim"], cfg["emb_dim"]),
)
def forward(self, x):
return self.layers(x)
class MultiHeadAttention(nn.Module):
def __init__(self, d_in, d_out, context_length, dropout, num_heads, qkv_bias=False):
super().__init__()
assert d_out % num_heads == 0, "d_out must be divisible by num_heads"
self.d_out = d_out
self.num_heads = num_heads
self.head_dim = d_out // num_heads # Reduce the projection dim to match desired output dim
self.W_query = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_key = nn.Linear(d_in, d_out, bias=qkv_bias)
self.W_value = nn.Linear(d_in, d_out, bias=qkv_bias)
self.out_proj = nn.Linear(d_out, d_out) # Linear layer to combine head outputs
self.dropout = nn.Dropout(dropout)
self.register_buffer('mask', torch.triu(torch.ones(context_length, context_length), diagonal=1))
def forward(self, x):
b, num_tokens, d_in = x.shape
keys = self.W_key(x) # Shape: (b, num_tokens, d_out)
queries = self.W_query(x)
values = self.W_value(x)
# We implicitly split the matrix by adding a `num_heads` dimension
# Unroll last dim: (b, num_tokens, d_out) -> (b, num_tokens, num_heads, head_dim)
keys = keys.view(b, num_tokens, self.num_heads, self.head_dim)
values = values.view(b, num_tokens, self.num_heads, self.head_dim)
queries = queries.view(b, num_tokens, self.num_heads, self.head_dim)
# Transpose: (b, num_tokens, num_heads, head_dim) -> (b, num_heads, num_tokens, head_dim)
keys = keys.transpose(1, 2)
queries = queries.transpose(1, 2)
values = values.transpose(1, 2)
# Compute scaled dot-product attention (aka self-attention) with a causal mask
attn_scores = queries @ keys.transpose(2, 3) # Dot product for each head
# Original mask truncated to the number of tokens and converted to boolean
mask_bool = self.mask.bool()[:num_tokens, :num_tokens]
# Use the mask to fill attention scores
attn_scores.masked_fill_(mask_bool, -torch.inf)
attn_weights = torch.softmax(attn_scores / keys.shape[-1]**0.5, dim=-1)
attn_weights = self.dropout(attn_weights)
# Shape: (b, num_tokens, num_heads, head_dim)
context_vec = (attn_weights @ values).transpose(1, 2)
# Combine heads, where self.d_out = self.num_heads * self.head_dim
context_vec = context_vec.contiguous().view(b, num_tokens, self.d_out)
context_vec = self.out_proj(context_vec) # optional projection
return context_vec
class LayerNorm(nn.Module):
def __init__(self, emb_dim):
super().__init__()
self.eps = 1e-5
self.scale = nn.Parameter(torch.ones(emb_dim))
self.shift = nn.Parameter(torch.zeros(emb_dim))
def forward(self, x):
mean = x.mean(dim=-1, keepdim=True)
var = x.var(dim=-1, keepdim=True, unbiased=False)
norm_x = (x - mean) / torch.sqrt(var + self.eps)
return self.scale * norm_x + self.shift
class TransformerBlock(nn.Module):
def __init__(self, cfg):
super().__init__()
self.att = MultiHeadAttention(
d_in=cfg["emb_dim"],
d_out=cfg["emb_dim"],
context_length=cfg["context_length"],
num_heads=cfg["n_heads"],
dropout=cfg["drop_rate"],
qkv_bias=cfg["qkv_bias"])
self.ff = FeedForward(cfg)
self.norm1 = LayerNorm(cfg["emb_dim"])
self.norm2 = LayerNorm(cfg["emb_dim"])
self.drop_shortcut = nn.Dropout(cfg["drop_rate"])
def forward(self, x):
# Shortcut connection for attention block
shortcut = x
x = self.norm1(x)
x = self.att(x) # Shape [batch_size, num_tokens, emb_size]
x = self.drop_shortcut(x)
x = x + shortcut # Add the original input back
# Shortcut connection for feed forward block
shortcut = x
x = self.norm2(x)
x = self.ff(x)
x = self.drop_shortcut(x)
x = x + shortcut # Add the original input back
return x
class GPTModel(nn.Module):
def __init__(self, cfg):
super().__init__()
self.tok_emb = nn.Embedding(cfg["vocab_size"], cfg["emb_dim"])
self.pos_emb = nn.Embedding(cfg["context_length"], cfg["emb_dim"])
self.drop_emb = nn.Dropout(cfg["drop_rate"])
self.trf_blocks = nn.Sequential(
*[TransformerBlock(cfg) for _ in range(cfg["n_layers"])])
self.final_norm = LayerNorm(cfg["emb_dim"])
self.out_head = nn.Linear(
cfg["emb_dim"], cfg["vocab_size"], bias=False
)
def forward(self, in_idx):
batch_size, seq_len = in_idx.shape
tok_embeds = self.tok_emb(in_idx)
pos_embeds = self.pos_emb(torch.arange(seq_len, device=in_idx.device))
x = tok_embeds + pos_embeds # Shape [batch_size, num_tokens, emb_size]
x = self.drop_emb(x)
x = self.trf_blocks(x)
x = self.final_norm(x)
logits = self.out_head(x)
return logits
GPT_CONFIG_124M = {
"vocab_size": 50257, # Vocabulary size
"context_length": 1024, # Context length
"emb_dim": 768, # Embedding dimension
"n_heads": 12, # Number of attention heads
"n_layers": 12, # Number of layers
"drop_rate": 0.1, # Dropout rate
"qkv_bias": False # Query-Key-Value bias
}
torch.manual_seed(123)
model = GPTModel(GPT_CONFIG_124M)
out = model(batch)
print("Input batch:\n", batch)
print("\nOutput shape:", out.shape)
print(out)
```
### **Kazi ya Kuamsha ya GELU**
```python
# From https://github.com/rasbt/LLMs-from-scratch/tree/main/ch04
class GELU(nn.Module):
def __init__(self):
super().__init__()
def forward(self, x):
return 0.5 * x * (1 + torch.tanh(
torch.sqrt(torch.tensor(2.0 / torch.pi)) *
(x + 0.044715 * torch.pow(x, 3))
))
```
#### **Madhumuni na Ufanisi**
- **GELU (Gaussian Error Linear Unit):** Kazi ya kuamsha ambayo inaingiza kutokuwa na mstari katika mfano.
- **Kuamsha kwa Ufanisi:** Tofauti na ReLU, ambayo inafuta maingizo hasi, GELU inachora kwa laini maingizo kuwa matokeo, ikiruhusu thamani ndogo, zisizo za sifuri kwa maingizo hasi.
- **Mwelekeo wa Kihesabu:**
<figure><img src="../../images/image (2) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
> [!TIP]
> Lengo la matumizi ya kazi hii baada ya tabaka za mstari ndani ya tabaka la FeedForward ni kubadilisha data ya mstari kuwa isiyo ya mstari ili kuruhusu mfano kujifunza uhusiano tata, usio wa mstari.
### **Mtandao wa Neva wa FeedForward**
_Mifano imeongezwa kama maoni ili kuelewa vyema mifano ya matrices:_
```python
# From https://github.com/rasbt/LLMs-from-scratch/tree/main/ch04
class FeedForward(nn.Module):
def __init__(self, cfg):
super().__init__()
self.layers = nn.Sequential(
nn.Linear(cfg["emb_dim"], 4 * cfg["emb_dim"]),
GELU(),
nn.Linear(4 * cfg["emb_dim"], cfg["emb_dim"]),
)
def forward(self, x):
# x shape: (batch_size, seq_len, emb_dim)
x = self.layers[0](x)# x shape: (batch_size, seq_len, 4 * emb_dim)
x = self.layers[1](x) # x shape remains: (batch_size, seq_len, 4 * emb_dim)
x = self.layers[2](x) # x shape: (batch_size, seq_len, emb_dim)
return x # Output shape: (batch_size, seq_len, emb_dim)
```
#### **Madhumuni na Ufanisi**
- **Mtandao wa FeedForward kwa Nafasi:** Inatumia mtandao wa kuunganishwa wa safu mbili kwa kila nafasi tofauti na sawa.
- **Maelezo ya Safu:**
- **Safu ya Kwanza ya Mstari:** Inapanua ukubwa kutoka `emb_dim` hadi `4 * emb_dim`.
- **Kazi ya GELU:** Inatumia isiyo ya laini.
- **Safu ya Pili ya Mstari:** Inapunguza ukubwa kurudi kwenye `emb_dim`.
> [!TIP]
> Kama unavyoona, mtandao wa Feed Forward unatumia safu 3. Ya kwanza ni safu ya mstari ambayo itazidisha ukubwa kwa 4 kwa kutumia uzito wa mstari (vigezo vya kufundisha ndani ya mfano). Kisha, kazi ya GELU inatumika katika ukubwa wote ili kuleta mabadiliko yasiyo ya laini ili kupata uwakilishi mzuri na hatimaye safu nyingine ya mstari inatumika kurudi kwenye ukubwa wa awali wa ukubwa.
### **Mekanismu ya Umakini wa Multi-Head**
Hii tayari ilielezwa katika sehemu ya awali.
#### **Madhumuni na Ufanisi**
- **Umakini wa Multi-Head wa Kujitazama:** Inaruhusu mfano kuzingatia nafasi tofauti ndani ya mlolongo wa ingizo wakati wa kuandika token.
- **Vipengele Muhimu:**
- **Maswali, Funguo, Thamani:** Mipango ya mstari ya ingizo, inayotumika kuhesabu alama za umakini.
- **Vichwa:** Mekanismu nyingi za umakini zinazoendesha kwa sambamba (`num_heads`), kila moja ikiwa na ukubwa mdogo (`head_dim`).
- **Alama za Umakini:** Zinahesabiwa kama bidhaa ya dot ya maswali na funguo, zimepimwa na kufichwa.
- **Kuficha:** Mask ya sababu inatumika kuzuia mfano kuzingatia token za baadaye (muhimu kwa mifano ya autoregressive kama GPT).
- **Uzito wa Umakini:** Softmax ya alama za umakini zilizofichwa na kupimwa.
- **Vector ya Muktadha:** Jumla yenye uzito ya thamani, kulingana na uzito wa umakini.
- **Mipango ya Matokeo:** Safu ya mstari ya kuunganisha matokeo ya vichwa vyote.
> [!TIP]
> Lengo la mtandao huu ni kupata uhusiano kati ya token katika muktadha sawa. Aidha, token zimegawanywa katika vichwa tofauti ili kuzuia overfitting ingawa uhusiano wa mwisho uliofanywa kwa kila kichwa unachanganywa mwishoni mwa mtandao huu.
>
> Aidha, wakati wa mafunzo **mask ya sababu** inatumika ili token za baadaye zisihesabiwe wakati wa kutafuta uhusiano maalum kwa token na **dropout** pia inatumika ili **kuzuia overfitting**.
### **Kiwango** Kurekebisha
```python
# From https://github.com/rasbt/LLMs-from-scratch/tree/main/ch04
class LayerNorm(nn.Module):
def __init__(self, emb_dim):
super().__init__()
self.eps = 1e-5 # Prevent division by zero during normalization.
self.scale = nn.Parameter(torch.ones(emb_dim))
self.shift = nn.Parameter(torch.zeros(emb_dim))
def forward(self, x):
mean = x.mean(dim=-1, keepdim=True)
var = x.var(dim=-1, keepdim=True, unbiased=False)
norm_x = (x - mean) / torch.sqrt(var + self.eps)
return self.scale * norm_x + self.shift
```
#### **Madhumuni na Ufanisi**
- **Layer Normalization:** Mbinu inayotumika kurekebisha ingizo kati ya vipengele (vipimo vya embedding) kwa kila mfano binafsi katika kundi.
- **Vipengele:**
- **`eps`:** Kiwango kidogo (`1e-5`) kinachoongezwa kwenye tofauti ili kuzuia kugawanya kwa sifuri wakati wa kurekebisha.
- **`scale` na `shift`:** Vigezo vinavyoweza kujifunza (`nn.Parameter`) vinavyomruhusu mfano kupima na kuhamasisha matokeo yaliyorekebishwa. Vimeanzishwa kuwa moja na sifuri, mtawalia.
- **Mchakato wa Kurekebisha:**
- **Hesabu Mean (`mean`):** Hesabu ya wastani wa ingizo `x` kati ya kipimo cha embedding (`dim=-1`), ikihifadhi kipimo kwa ajili ya kueneza (`keepdim=True`).
- **Hesabu Variance (`var`):** Hesabu ya tofauti ya `x` kati ya kipimo cha embedding, pia ikihifadhi kipimo. Kigezo `unbiased=False` kinahakikisha kwamba tofauti inahesabiwa kwa kutumia mhesabu wa upendeleo (kugawanya kwa `N` badala ya `N-1`), ambayo ni sahihi wakati wa kurekebisha juu ya vipengele badala ya sampuli.
- **Kurekebisha (`norm_x`):** Inapunguza wastani kutoka `x` na kugawanya kwa mzizi wa tofauti pamoja na `eps`.
- **Pima na Hamisha:** Inatumia vigezo vinavyoweza kujifunza `scale` na `shift` kwa matokeo yaliyorekebishwa.
> [!TIP]
> Lengo ni kuhakikisha wastani wa 0 na tofauti ya 1 kati ya vipimo vyote vya token sawa. Lengo hili ni **kuimarisha mafunzo ya mitandao ya neva ya kina** kwa kupunguza mabadiliko ya ndani ya covariate, ambayo inahusisha mabadiliko katika usambazaji wa uhamasishaji wa mtandao kutokana na kubadilisha vigezo wakati wa mafunzo.
### **Transformer Block**
_Shapes zimeongezwa kama maoni ili kuelewa vyema shapes za matrices:_
```python
# From https://github.com/rasbt/LLMs-from-scratch/tree/main/ch04
class TransformerBlock(nn.Module):
def __init__(self, cfg):
super().__init__()
self.att = MultiHeadAttention(
d_in=cfg["emb_dim"],
d_out=cfg["emb_dim"],
context_length=cfg["context_length"],
num_heads=cfg["n_heads"],
dropout=cfg["drop_rate"],
qkv_bias=cfg["qkv_bias"]
)
self.ff = FeedForward(cfg)
self.norm1 = LayerNorm(cfg["emb_dim"])
self.norm2 = LayerNorm(cfg["emb_dim"])
self.drop_shortcut = nn.Dropout(cfg["drop_rate"])
def forward(self, x):
# x shape: (batch_size, seq_len, emb_dim)
# Shortcut connection for attention block
shortcut = x # shape: (batch_size, seq_len, emb_dim)
x = self.norm1(x) # shape remains (batch_size, seq_len, emb_dim)
x = self.att(x) # shape: (batch_size, seq_len, emb_dim)
x = self.drop_shortcut(x) # shape remains (batch_size, seq_len, emb_dim)
x = x + shortcut # shape: (batch_size, seq_len, emb_dim)
# Shortcut connection for feedforward block
shortcut = x # shape: (batch_size, seq_len, emb_dim)
x = self.norm2(x) # shape remains (batch_size, seq_len, emb_dim)
x = self.ff(x) # shape: (batch_size, seq_len, emb_dim)
x = self.drop_shortcut(x) # shape remains (batch_size, seq_len, emb_dim)
x = x + shortcut # shape: (batch_size, seq_len, emb_dim)
return x # Output shape: (batch_size, seq_len, emb_dim)
```
#### **Madhumuni na Ufanisi**
- **Muundo wa Tabaka:** Inachanganya umakini wa vichwa vingi, mtandao wa feedforward, urekebishaji wa tabaka, na muunganisho wa ziada.
- **Urekebishaji wa Tabaka:** Unatumika kabla ya tabaka za umakini na feedforward kwa mafunzo thabiti.
- **Muunganisho wa Ziada (Njia Fupi):** Ongeza ingizo la tabaka kwa matokeo yake ili kuboresha mtiririko wa gradient na kuwezesha mafunzo ya mitandao yenye kina.
- **Dropout:** Unatumika baada ya tabaka za umakini na feedforward kwa ajili ya urekebishaji.
#### **Ufanisi wa Hatua kwa Hatua**
1. **Njia ya Kwanza ya Ziada (Umakini wa Kibinafsi):**
- **Ingizo (`shortcut`):** Hifadhi ingizo la awali kwa muunganisho wa ziada.
- **Urekebishaji wa Tabaka (`norm1`):** Rekebisha ingizo.
- **Umakini wa Vichwa Vingi (`att`):** Tumia umakini wa kibinafsi.
- **Dropout (`drop_shortcut`):** Tumia dropout kwa urekebishaji.
- **Ongeza Ziada (`x + shortcut`):** Changanya na ingizo la awali.
2. **Njia ya Pili ya Ziada (FeedForward):**
- **Ingizo (`shortcut`):** Hifadhi ingizo lililosasishwa kwa muunganisho wa ziada unaofuata.
- **Urekebishaji wa Tabaka (`norm2`):** Rekebisha ingizo.
- **Mtandao wa FeedForward (`ff`):** Tumia mabadiliko ya feedforward.
- **Dropout (`drop_shortcut`):** Tumia dropout.
- **Ongeza Ziada (`x + shortcut`):** Changanya na ingizo kutoka kwa njia ya kwanza ya ziada.
> [!TIP]
> Block ya transformer inakusanya mitandao yote pamoja na kutumia **urekebishaji** na **dropouts** kuboresha utulivu wa mafunzo na matokeo.\
> Kumbuka jinsi dropouts zinavyofanywa baada ya matumizi ya kila mtandao wakati urekebishaji unatumika kabla.
>
> Zaidi ya hayo, inatumia njia fupi ambazo zinajumuisha **kuongeza matokeo ya mtandao na ingizo lake**. Hii husaidia kuzuia tatizo la gradient inayopotea kwa kuhakikisha kwamba tabaka za mwanzo zinachangia "kiasi" sawa na zile za mwisho.
### **GPTModel**
_Mifano imeongezwa kama maoni ili kuelewa vyema mifano ya matrices:_
```python
# From https://github.com/rasbt/LLMs-from-scratch/tree/main/ch04
class GPTModel(nn.Module):
def __init__(self, cfg):
super().__init__()
self.tok_emb = nn.Embedding(cfg["vocab_size"], cfg["emb_dim"])
# shape: (vocab_size, emb_dim)
self.pos_emb = nn.Embedding(cfg["context_length"], cfg["emb_dim"])
# shape: (context_length, emb_dim)
self.drop_emb = nn.Dropout(cfg["drop_rate"])
self.trf_blocks = nn.Sequential(
*[TransformerBlock(cfg) for _ in range(cfg["n_layers"])]
)
# Stack of TransformerBlocks
self.final_norm = LayerNorm(cfg["emb_dim"])
self.out_head = nn.Linear(cfg["emb_dim"], cfg["vocab_size"], bias=False)
# shape: (emb_dim, vocab_size)
def forward(self, in_idx):
# in_idx shape: (batch_size, seq_len)
batch_size, seq_len = in_idx.shape
# Token embeddings
tok_embeds = self.tok_emb(in_idx)
# shape: (batch_size, seq_len, emb_dim)
# Positional embeddings
pos_indices = torch.arange(seq_len, device=in_idx.device)
# shape: (seq_len,)
pos_embeds = self.pos_emb(pos_indices)
# shape: (seq_len, emb_dim)
# Add token and positional embeddings
x = tok_embeds + pos_embeds # Broadcasting over batch dimension
# x shape: (batch_size, seq_len, emb_dim)
x = self.drop_emb(x) # Dropout applied
# x shape remains: (batch_size, seq_len, emb_dim)
x = self.trf_blocks(x) # Pass through Transformer blocks
# x shape remains: (batch_size, seq_len, emb_dim)
x = self.final_norm(x) # Final LayerNorm
# x shape remains: (batch_size, seq_len, emb_dim)
logits = self.out_head(x) # Project to vocabulary size
# logits shape: (batch_size, seq_len, vocab_size)
return logits # Output shape: (batch_size, seq_len, vocab_size)
```
#### **Madhumuni na Ufanisi**
- **Embedding Layers:**
- **Token Embeddings (`tok_emb`):** Hubadilisha viashiria vya token kuwa embeddings. Kama ukumbusho, hizi ni uzito zinazotolewa kwa kila kipimo cha kila token katika msamiati.
- **Positional Embeddings (`pos_emb`):** Ongeza taarifa za nafasi kwa embeddings ili kukamata mpangilio wa token. Kama ukumbusho, hizi ni uzito zinazotolewa kwa token kulingana na nafasi yake katika maandiko.
- **Dropout (`drop_emb`):** Inatumika kwa embeddings kwa ajili ya regularisation.
- **Transformer Blocks (`trf_blocks`):** Safu ya `n_layers` transformer blocks ili kushughulikia embeddings.
- **Final Normalization (`final_norm`):** Kiwango cha normalization kabla ya safu ya matokeo.
- **Output Layer (`out_head`):** Inatabiri hali za mwisho zilizofichwa kwa ukubwa wa msamiati ili kutoa logits kwa ajili ya utabiri.
> [!TIP]
> Lengo la darasa hili ni kutumia mitandao mingine yote iliyotajwa ili **kutabiri token inayofuata katika mfuatano**, ambayo ni muhimu kwa kazi kama vile uzalishaji wa maandiko.
>
> Kumbuka jinsi itakavy **tumia blocks za transformer nyingi kadri zilivyoonyeshwa** na kwamba kila block ya transformer inatumia neti moja ya multi-head attestation, neti moja ya feed forward na normalizations kadhaa. Hivyo kama blocks 12 za transformer zinatumika, ongeza hii kwa 12.
>
> Zaidi ya hayo, safu ya **normalization** inaongezwa **kabla** ya **matokeo** na safu ya mwisho ya linear inatumika mwishoni kupata matokeo yenye vipimo sahihi. Kumbuka jinsi kila vector ya mwisho ina ukubwa wa msamiati ulio tumika. Hii ni kwa sababu inajaribu kupata uwezekano kwa kila token inayowezekana ndani ya msamiati.
## Idadi ya Vigezo vya kufundisha
Baada ya muundo wa GPT kufafanuliwa, inawezekana kugundua idadi ya vigezo vya kufundisha:
```python
GPT_CONFIG_124M = {
"vocab_size": 50257, # Vocabulary size
"context_length": 1024, # Context length
"emb_dim": 768, # Embedding dimension
"n_heads": 12, # Number of attention heads
"n_layers": 12, # Number of layers
"drop_rate": 0.1, # Dropout rate
"qkv_bias": False # Query-Key-Value bias
}
model = GPTModel(GPT_CONFIG_124M)
total_params = sum(p.numel() for p in model.parameters())
print(f"Total number of parameters: {total_params:,}")
# Total number of parameters: 163,009,536
```
### **Hatua kwa Hatua Hesabu**
#### **1. Tabaka za Kuunganisha: Kuunganisha Tokeni & Kuunganisha Nafasi**
- **Tabaka:** `nn.Embedding(vocab_size, emb_dim)`
- **Vigezo:** `vocab_size * emb_dim`
```python
token_embedding_params = 50257 * 768 = 38,597,376
```
- **Tabaka:** `nn.Embedding(context_length, emb_dim)`
- **Vigezo:** `context_length * emb_dim`
```python
position_embedding_params = 1024 * 768 = 786,432
```
**Jumla ya Vigezo vya Kuunganisha**
```python
embedding_params = token_embedding_params + position_embedding_params
embedding_params = 38,597,376 + 786,432 = 39,383,808
```
#### **2. Transformer Blocks**
Kuna blocks 12 za transformer, hivyo tutahesabu vigezo kwa block moja kisha kuzidisha kwa 12.
**Parameters per Transformer Block**
**a. Multi-Head Attention**
- **Components:**
- **Query Linear Layer (`W_query`):** `nn.Linear(emb_dim, emb_dim, bias=False)`
- **Key Linear Layer (`W_key`):** `nn.Linear(emb_dim, emb_dim, bias=False)`
- **Value Linear Layer (`W_value`):** `nn.Linear(emb_dim, emb_dim, bias=False)`
- **Output Projection (`out_proj`):** `nn.Linear(emb_dim, emb_dim)`
- **Calculations:**
- **Kila moja ya `W_query`, `W_key`, `W_value`:**
```python
qkv_params = emb_dim * emb_dim = 768 * 768 = 589,824
```
Kwa kuwa kuna tabaka tatu kama hizo:
```python
total_qkv_params = 3 * qkv_params = 3 * 589,824 = 1,769,472
```
- **Output Projection (`out_proj`):**
```python
out_proj_params = (emb_dim * emb_dim) + emb_dim = (768 * 768) + 768 = 589,824 + 768 = 590,592
```
- **Jumla ya Vigezo vya Multi-Head Attention:**
```python
mha_params = total_qkv_params + out_proj_params
mha_params = 1,769,472 + 590,592 = 2,360,064
```
**b. FeedForward Network**
- **Components:**
- **First Linear Layer:** `nn.Linear(emb_dim, 4 * emb_dim)`
- **Second Linear Layer:** `nn.Linear(4 * emb_dim, emb_dim)`
- **Calculations:**
- **First Linear Layer:**
```python
ff_first_layer_params = (emb_dim * 4 * emb_dim) + (4 * emb_dim)
ff_first_layer_params = (768 * 3072) + 3072 = 2,359,296 + 3,072 = 2,362,368
```
- **Second Linear Layer:**
```python
ff_second_layer_params = (4 * emb_dim * emb_dim) + emb_dim
ff_second_layer_params = (3072 * 768) + 768 = 2,359,296 + 768 = 2,360,064
```
- **Jumla ya Vigezo vya FeedForward:**
```python
ff_params = ff_first_layer_params + ff_second_layer_params
ff_params = 2,362,368 + 2,360,064 = 4,722,432
```
**c. Layer Normalizations**
- **Components:**
- Mbili `LayerNorm` instances kwa block.
- Kila `LayerNorm` ina vigezo `2 * emb_dim` (scale na shift).
- **Calculations:**
```python
layer_norm_params_per_block = 2 * (2 * emb_dim) = 2 * 768 * 2 = 3,072
```
**d. Jumla ya Vigezo kwa Transformer Block**
```python
pythonCopy codeparams_per_block = mha_params + ff_params + layer_norm_params_per_block
params_per_block = 2,360,064 + 4,722,432 + 3,072 = 7,085,568
```
**Jumla ya Paramita kwa Vizuizi Vyote vya Transformer**
```python
pythonCopy codetotal_transformer_blocks_params = params_per_block * n_layers
total_transformer_blocks_params = 7,085,568 * 12 = 85,026,816
```
#### **3. Tabaka la Mwisho**
**a. Kurekebisha Tabaka la Mwisho**
- **Parameta:** `2 * emb_dim` (kubwa na kuhamasisha)
```python
pythonCopy codefinal_layer_norm_params = 2 * 768 = 1,536
```
**b. Safu ya Kutolewa (`out_head`)**
- **Safu:** `nn.Linear(emb_dim, vocab_size, bias=False)`
- **Parameta:** `emb_dim * vocab_size`
```python
pythonCopy codeoutput_projection_params = 768 * 50257 = 38,597,376
```
#### **4. Kuangalia Mipangilio Yote**
```python
pythonCopy codetotal_params = (
embedding_params +
total_transformer_blocks_params +
final_layer_norm_params +
output_projection_params
)
total_params = (
39,383,808 +
85,026,816 +
1,536 +
38,597,376
)
total_params = 163,009,536
```
## Generate Text
Kuwa na mfano unaotabiri token inayofuata kama ile ya awali, inahitajika tu kuchukua thamani za token za mwisho kutoka kwa matokeo (kama zitakuwa zile za token iliyotabiriwa), ambazo zitakuwa **thamani kwa kila kipengee katika msamiati** na kisha kutumia kazi ya `softmax` kubadilisha vipimo kuwa uwezekano vinavyos suma 1 na kisha kupata index ya kipengee kikubwa zaidi, ambacho kitakuwa index ya neno ndani ya msamiati.
Code from [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch04/01_main-chapter-code/ch04.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch04/01_main-chapter-code/ch04.ipynb):
```python
def generate_text_simple(model, idx, max_new_tokens, context_size):
# idx is (batch, n_tokens) array of indices in the current context
for _ in range(max_new_tokens):
# Crop current context if it exceeds the supported context size
# E.g., if LLM supports only 5 tokens, and the context size is 10
# then only the last 5 tokens are used as context
idx_cond = idx[:, -context_size:]
# Get the predictions
with torch.no_grad():
logits = model(idx_cond)
# Focus only on the last time step
# (batch, n_tokens, vocab_size) becomes (batch, vocab_size)
logits = logits[:, -1, :]
# Apply softmax to get probabilities
probas = torch.softmax(logits, dim=-1) # (batch, vocab_size)
# Get the idx of the vocab entry with the highest probability value
idx_next = torch.argmax(probas, dim=-1, keepdim=True) # (batch, 1)
# Append sampled index to the running sequence
idx = torch.cat((idx, idx_next), dim=1) # (batch, n_tokens+1)
return idx
start_context = "Hello, I am"
encoded = tokenizer.encode(start_context)
print("encoded:", encoded)
encoded_tensor = torch.tensor(encoded).unsqueeze(0)
print("encoded_tensor.shape:", encoded_tensor.shape)
model.eval() # disable dropout
out = generate_text_simple(
model=model,
idx=encoded_tensor,
max_new_tokens=6,
context_size=GPT_CONFIG_124M["context_length"]
)
print("Output:", out)
print("Output length:", len(out[0]))
```
## Marejeo
- [https://www.manning.com/books/build-a-large-language-model-from-scratch](https://www.manning.com/books/build-a-large-language-model-from-scratch)

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# 7.0. LoRA Improvements in fine-tuning
## LoRA Improvements
> [!TIP]
> Matumizi ya **LoRA hupunguza sana hesabu** inayohitajika ili **kurekebisha** mifano ambayo tayari imefunzwa.
LoRA inafanya iwezekane kurekebisha **mifano mikubwa** kwa ufanisi kwa kubadilisha tu **sehemu ndogo** ya mfano. Inapunguza idadi ya vigezo unavyohitaji kufundisha, ikihifadhi **kumbukumbu** na **rasilimali za kompyuta**. Hii ni kwa sababu:
1. **Inapunguza Idadi ya Vigezo Vinavyoweza Kufundishwa**: Badala ya kuboresha matrix nzima ya uzito katika mfano, LoRA **inaigawanya** matrix ya uzito katika matrices mbili ndogo (zinazoitwa **A** na **B**). Hii inafanya mafunzo kuwa **haraka** na inahitaji **kumbukumbu kidogo** kwa sababu vigezo vichache vinahitaji kuboreshwa.
1. Hii ni kwa sababu badala ya kuhesabu sasisho kamili la uzito wa safu (matrix), inakadiria kuwa ni bidhaa ya matrices 2 ndogo ikipunguza sasisho la kuhesabu:\
<figure><img src="../../images/image (9) (1).png" alt=""><figcaption></figcaption></figure>
2. **Inahifadhi Uzito wa Mfano wa Asili Bila Kubadilika**: LoRA inakuwezesha kuhifadhi uzito wa mfano wa asili kuwa sawa, na inasasisha tu **matrices ndogo mpya** (A na B). Hii ni muhimu kwa sababu inamaanisha kuwa maarifa ya asili ya mfano yanahifadhiwa, na unabadilisha tu kile kinachohitajika.
3. **Kurekebisha kwa Ufanisi Kazi Maalum**: Unapotaka kuadaptisha mfano kwa **kazi mpya**, unaweza tu kufundisha **matrices ndogo za LoRA** (A na B) huku ukiacha sehemu nyingine ya mfano kama ilivyo. Hii ni **ya ufanisi zaidi** kuliko kufundisha upya mfano mzima.
4. **Ufanisi wa Hifadhi**: Baada ya kurekebisha, badala ya kuhifadhi **mfano mpya mzima** kwa kila kazi, unahitaji tu kuhifadhi **matrices za LoRA**, ambazo ni ndogo sana ikilinganishwa na mfano mzima. Hii inafanya iwe rahisi kuadaptisha mfano kwa kazi nyingi bila kutumia hifadhi nyingi.
Ili kutekeleza LoraLayers badala ya zile za Linear wakati wa kurekebisha, msimbo huu unapendekezwa hapa [https://github.com/rasbt/LLMs-from-scratch/blob/main/appendix-E/01_main-chapter-code/appendix-E.ipynb](https://github.com/rasbt/LLMs-from-scratch/blob/main/appendix-E/01_main-chapter-code/appendix-E.ipynb):
```python
import math
# Create the LoRA layer with the 2 matrices and the alpha
class LoRALayer(torch.nn.Module):
def __init__(self, in_dim, out_dim, rank, alpha):
super().__init__()
self.A = torch.nn.Parameter(torch.empty(in_dim, rank))
torch.nn.init.kaiming_uniform_(self.A, a=math.sqrt(5)) # similar to standard weight initialization
self.B = torch.nn.Parameter(torch.zeros(rank, out_dim))
self.alpha = alpha
def forward(self, x):
x = self.alpha * (x @ self.A @ self.B)
return x
# Combine it with the linear layer
class LinearWithLoRA(torch.nn.Module):
def __init__(self, linear, rank, alpha):
super().__init__()
self.linear = linear
self.lora = LoRALayer(
linear.in_features, linear.out_features, rank, alpha
)
def forward(self, x):
return self.linear(x) + self.lora(x)
# Replace linear layers with LoRA ones
def replace_linear_with_lora(model, rank, alpha):
for name, module in model.named_children():
if isinstance(module, torch.nn.Linear):
# Replace the Linear layer with LinearWithLoRA
setattr(model, name, LinearWithLoRA(module, rank, alpha))
else:
# Recursively apply the same function to child modules
replace_linear_with_lora(module, rank, alpha)
```
## Marejeo
- [https://www.manning.com/books/build-a-large-language-model-from-scratch](https://www.manning.com/books/build-a-large-language-model-from-scratch)

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# 7.2. Kurekebisha ili kufuata maelekezo
> [!TIP]
> Lengo la sehemu hii ni kuonyesha jinsi ya **kurekebisha mfano ulio tayari tayari kufuata maelekezo** badala ya kuzalisha tu maandiko, kwa mfano, kujibu kazi kama roboti ya mazungumzo.
## Dataset
Ili kurekebisha LLM kufuata maelekezo, inahitajika kuwa na dataset yenye maelekezo na majibu ili kurekebisha LLM. Kuna mifano tofauti ya kufundisha LLM kufuata maelekezo, kwa mfano:
- Mfano wa mtindo wa ombi la Apply Alpaca:
```csharp
Below is an instruction that describes a task. Write a response that appropriately completes the request.
### Instruction:
Calculate the area of a circle with a radius of 5 units.
### Response:
The area of a circle is calculated using the formula \( A = \pi r^2 \). Plugging in the radius of 5 units:
\( A = \pi (5)^2 = \pi \times 25 = 25\pi \) square units.
```
- Mfano wa Mtindo wa Phi-3 Prompt:
```vbnet
<|User|>
Can you explain what gravity is in simple terms?
<|Assistant|>
Absolutely! Gravity is a force that pulls objects toward each other.
```
Kufundisha LLM kwa kutumia seti hizi za data badala ya maandiko ya kawaida husaidia LLM kuelewa kwamba inahitaji kutoa majibu maalum kwa maswali inayopewa.
Kwa hivyo, moja ya mambo ya kwanza ya kufanya na seti ya data inayojumuisha maombi na majibu ni kuunda mfano wa tarehe hiyo katika muundo wa ombi unaotakiwa, kama:
```python
# Code from https://github.com/rasbt/LLMs-from-scratch/blob/main/ch07/01_main-chapter-code/ch07.ipynb
def format_input(entry):
instruction_text = (
f"Below is an instruction that describes a task. "
f"Write a response that appropriately completes the request."
f"\n\n### Instruction:\n{entry['instruction']}"
)
input_text = f"\n\n### Input:\n{entry['input']}" if entry["input"] else ""
return instruction_text + input_text
model_input = format_input(data[50])
desired_response = f"\n\n### Response:\n{data[50]['output']}"
print(model_input + desired_response)
```
Kisha, kama kawaida, inahitajika kutenganisha dataset katika seti za mafunzo, uthibitisho na upimaji.
## Batching & Data Loaders
Kisha, inahitajika kubatch kila ingizo na matokeo yanayotarajiwa kwa mafunzo. Kwa hili, inahitajika:
- Tokenize maandiko
- Pad sampuli zote hadi urefu sawa (kawaida urefu utakuwa mkubwa kama urefu wa muktadha ulitumika kabla ya kufundisha LLM)
- Unda token zinazotarajiwa kwa kuhamasisha 1 ingizo katika kazi ya collate ya kawaida
- Badilisha baadhi ya token za padding na -100 ili kuziondoa kutoka kwa hasara ya mafunzo: Baada ya token ya kwanza `endoftext`, badilisha token zote nyingine za `endoftext` kwa -100 (kwa sababu kutumia `cross_entropy(...,ignore_index=-100)` inamaanisha kwamba itapuuzilia mbali malengo yenye -100)
- \[Hiari\] Ficha kwa kutumia -100 pia token zote zinazohusiana na swali ili LLM ijifunze tu jinsi ya kuzalisha jibu. Katika mtindo wa Apply Alpaca hii itamaanisha kuficha kila kitu hadi `### Response:`
Kwa hili lililoundwa, ni wakati wa kuunda data loaders kwa kila dataset (mafunzo, uthibitisho na upimaji).
## Load pre-trained LLM & Fine tune & Loss Checking
Inahitajika kupakia LLM iliyofundishwa awali ili kuifanyia fine tune. Hii tayari imejadiliwa katika kurasa nyingine. Kisha, inawezekana kutumia kazi ya mafunzo iliyotumika awali ili kuifanyia fine tune LLM.
Wakati wa mafunzo pia inawezekana kuona jinsi hasara ya mafunzo na hasara ya uthibitisho inavyobadilika wakati wa epochs ili kuona kama hasara inapata kupungua na kama overfitting inatokea.\
Kumbuka kwamba overfitting inatokea wakati hasara ya mafunzo inapata kupungua lakini hasara ya uthibitisho haipungui au hata inaongezeka. Ili kuepuka hili, jambo rahisi zaidi la kufanya ni kusitisha mafunzo katika epoch ambapo tabia hii inaanza.
## Response Quality
Kwa kuwa hii si fine-tune ya uainishaji ambapo inawezekana kuamini zaidi mabadiliko ya hasara, pia ni muhimu kuangalia ubora wa majibu katika seti ya upimaji. Kwa hivyo, inapendekezwa kukusanya majibu yaliyoundwa kutoka kwa seti zote za upimaji na **kuangalia ubora wao kwa mikono** ili kuona kama kuna majibu mabaya (kumbuka kwamba inawezekana kwa LLM kuunda kwa usahihi muundo na sintaksia ya sentensi ya jibu lakini kutoa jibu kabisa lisilo sahihi. Mabadiliko ya hasara hayatadhihirisha tabia hii).\
Kumbuka kwamba pia inawezekana kufanya ukaguzi huu kwa kupitisha majibu yaliyoundwa na majibu yanayotarajiwa kwa **LLMs nyingine na kuwauliza wathmini majibu**.
Jaribio lingine la kufanya ili kuthibitisha ubora wa majibu:
1. **Measuring Massive Multitask Language Understanding (**[**MMLU**](https://arxiv.org/abs/2009.03300)**):** MMLU inakadiria maarifa ya mfano na uwezo wa kutatua matatizo katika masomo 57, ikiwa ni pamoja na humanities, sayansi, na zaidi. Inatumia maswali ya uchaguzi mwingi kutathmini uelewa katika ngazi mbalimbali za ugumu, kutoka msingi hadi kitaaluma ya juu.
2. [**LMSYS Chatbot Arena**](https://arena.lmsys.org): Jukwaa hili linawawezesha watumiaji kulinganisha majibu kutoka kwa chatbots tofauti kwa upande mmoja. Watumiaji wanaingiza kichocheo, na chatbots nyingi zinazalisha majibu ambayo yanaweza kulinganishwa moja kwa moja.
3. [**AlpacaEval**](https://github.com/tatsu-lab/alpaca_eval)**:** AlpacaEval ni mfumo wa tathmini wa kiotomatiki ambapo LLM ya juu kama GPT-4 inakadiria majibu ya mifano mingine kwa kichocheo mbalimbali.
4. **General Language Understanding Evaluation (**[**GLUE**](https://gluebenchmark.com/)**):** GLUE ni mkusanyiko wa kazi tisa za uelewa wa lugha ya asili, ikiwa ni pamoja na uchambuzi wa hisia, uhusiano wa maandiko, na kujibu maswali.
5. [**SuperGLUE**](https://super.gluebenchmark.com/)**:** Kujenga juu ya GLUE, SuperGLUE inajumuisha kazi ngumu zaidi zilizoundwa kuwa ngumu kwa mifano ya sasa.
6. **Beyond the Imitation Game Benchmark (**[**BIG-bench**](https://github.com/google/BIG-bench)**):** BIG-bench ni kipimo kikubwa chenye kazi zaidi ya 200 zinazotest uwezo wa mfano katika maeneo kama vile mantiki, tafsiri, na kujibu maswali.
7. **Holistic Evaluation of Language Models (**[**HELM**](https://crfm.stanford.edu/helm/lite/latest/)**):** HELM inatoa tathmini kamili katika metriki mbalimbali kama vile usahihi, uimara, na haki.
8. [**OpenAI Evals**](https://github.com/openai/evals)**:** Mfumo wa tathmini wa chanzo wazi kutoka OpenAI unaowezesha kupima mifano ya AI kwenye kazi za kawaida na za kiwango.
9. [**HumanEval**](https://github.com/openai/human-eval)**:** Mkusanyiko wa matatizo ya programu yanayotumika kutathmini uwezo wa kizazi cha msimbo wa mifano ya lugha.
10. **Stanford Question Answering Dataset (**[**SQuAD**](https://rajpurkar.github.io/SQuAD-explorer/)**):** SQuAD inajumuisha maswali kuhusu makala za Wikipedia, ambapo mifano inapaswa kuelewa maandiko ili kujibu kwa usahihi.
11. [**TriviaQA**](https://nlp.cs.washington.edu/triviaqa/)**:** Mkusanyiko mkubwa wa maswali na majibu ya trivia, pamoja na hati za ushahidi.
na mengi zaidi
## Follow instructions fine-tuning code
Unaweza kupata mfano wa msimbo wa kufanya fine tuning hii katika [https://github.com/rasbt/LLMs-from-scratch/blob/main/ch07/01_main-chapter-code/gpt_instruction_finetuning.py](https://github.com/rasbt/LLMs-from-scratch/blob/main/ch07/01_main-chapter-code/gpt_instruction_finetuning.py)
## References
- [https://www.manning.com/books/build-a-large-language-model-from-scratch](https://www.manning.com/books/build-a-large-language-model-from-scratch)

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@ -13,7 +13,7 @@ Unapaswa kuanza kwa kusoma chapisho hili kwa baadhi ya dhana za msingi unazopasw
## 1. Tokenization
> [!TIP]
> Lengo la awamu hii ya awali ni rahisi sana: **Gawanya ingizo katika token (ids) kwa njia ambayo ina maana**.
> Lengo la awamu hii ya awali ni rahisi sana: **Gawanya ingizo katika tokeni (ids) kwa njia ambayo ina maana**.
{{#ref}}
1.-tokenizing.md
@ -31,10 +31,10 @@ Unapaswa kuanza kwa kusoma chapisho hili kwa baadhi ya dhana za msingi unazopasw
## 3. Token Embeddings
> [!TIP]
> Lengo la awamu hii ya tatu ni rahisi sana: **Patia kila moja ya token zilizopita katika msamiati vector ya vipimo vinavyotakiwa ili kufundisha mfano.** Kila neno katika msamiati litakuwa na pointi katika nafasi ya vipimo X.\
> Lengo la awamu hii ya tatu ni rahisi sana: **Patia kila moja ya tokeni za awali katika msamiati vector ya vipimo vinavyotakiwa ili kufundisha mfano.** Kila neno katika msamiati litakuwa na pointi katika nafasi ya vipimo X.\
> Kumbuka kwamba awali nafasi ya kila neno katika nafasi inaanzishwa "kwa bahati nasibu" na nafasi hizi ni vigezo vinavyoweza kufundishwa (vitaboreshwa wakati wa mafunzo).
>
> Zaidi ya hayo, wakati wa token embedding **tabaka lingine la embeddings linaundwa** ambalo linawakilisha (katika kesi hii) **nafasi halisi ya neno katika sentensi ya mafunzo**. Kwa njia hii neno katika nafasi tofauti katika sentensi litakuwa na uwakilishi tofauti (maana).
> Zaidi ya hayo, wakati wa kuingiza tokeni **tabaka lingine la kuingiza linaundwa** ambalo linawakilisha (katika kesi hii) **nafasi halisi ya neno katika sentensi ya mafunzo**. Kwa njia hii neno katika nafasi tofauti katika sentensi litakuwa na uwakilishi tofauti (maana).
{{#ref}}
3.-token-embeddings.md
@ -43,7 +43,7 @@ Unapaswa kuanza kwa kusoma chapisho hili kwa baadhi ya dhana za msingi unazopasw
## 4. Attention Mechanisms
> [!TIP]
> Lengo la awamu hii ya nne ni rahisi sana: **Tumia baadhi ya mitambo ya umakini**. Hizi zitakuwa **tabaka nyingi zinazojirudia** ambazo zitakuwa **zinakamata uhusiano wa neno katika msamiati na majirani zake katika sentensi ya sasa inayotumika kufundisha LLM**.\
> Lengo la awamu hii ya nne ni rahisi sana: **Tumia baadhi ya mitambo ya umakini**. Hizi zitakuwa tabaka nyingi **zinazorudiwa** ambazo zitakuwa **zinakamata uhusiano wa neno katika msamiati na majirani zake katika sentensi ya sasa inayotumika kufundisha LLM**.\
> Tabaka nyingi zinatumika kwa hili, hivyo vigezo vingi vinavyoweza kufundishwa vitakuwa vinakamata taarifa hii.
{{#ref}}
@ -64,7 +64,7 @@ Unapaswa kuanza kwa kusoma chapisho hili kwa baadhi ya dhana za msingi unazopasw
## 6. Pre-training & Loading models
> [!TIP]
> Lengo la awamu hii ya sita ni rahisi sana: **Fundisha mfano kutoka mwanzo**. Kwa hili muundo wa awali wa LLM utatumika na miduara fulani ikipita juu ya seti za data kwa kutumia kazi za hasara zilizofafanuliwa na msaidizi kufundisha vigezo vyote vya mfano.
> Lengo la awamu hii ya sita ni rahisi sana: **Fundisha mfano kutoka mwanzo**. Kwa hili muundo wa awali wa LLM utatumika na miduara fulani ikipita juu ya seti za data kwa kutumia kazi zilizofafanuliwa za hasara na msaidizi kufundisha vigezo vyote vya mfano.
{{#ref}}
6.-pre-training-and-loading-models.md
@ -91,7 +91,7 @@ Unapaswa kuanza kwa kusoma chapisho hili kwa baadhi ya dhana za msingi unazopasw
## 7.2. Fine-Tuning to follow instructions
> [!TIP]
> Lengo la sehemu hii ni kuonyesha jinsi ya **kurekebisha mfano uliofundishwa tayari kufuata maelekezo** badala ya tu kuzalisha maandiko, kwa mfano, kujibu kazi kama roboti ya mazungumzo.
> Lengo la sehemu hii ni kuonyesha jinsi ya **kurekebisha mfano uliofundishwa tayari ili kufuata maagizo** badala ya tu kuzalisha maandiko, kwa mfano, kujibu kazi kama roboti ya mazungumzo.
{{#ref}}
7.2.-fine-tuning-to-follow-instructions.md