Commit
·
8ac9b44
1
Parent(s):
e19b1b8
Upload model
Browse files- config.json +2 -2
- nano_gpt_model.py +134 -0
config.json
CHANGED
@@ -3,8 +3,8 @@
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"SimpleStories4MModel"
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],
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"auto_map": {
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"AutoConfig": "
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"AutoModelForCausalLM": "
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},
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"block_size": 1080,
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"dropout": 0.1,
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"SimpleStories4MModel"
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],
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"auto_map": {
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"AutoConfig": "configuration_ss4m.SimpleStories4MConfig",
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"AutoModelForCausalLM": "modeling_ss4m.SimpleStories4MModel"
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},
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"block_size": 1080,
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"dropout": 0.1,
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nano_gpt_model.py
ADDED
@@ -0,0 +1,134 @@
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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# model architecture
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class AttentionHead(nn.Module):
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"""a single head of self attention"""
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def __init__(self, n_embed, head_size, block_size, dropout):
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super().__init__()
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self.key = nn.Linear(n_embed, head_size, bias=False)
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self.query = nn.Linear(n_embed, head_size, bias=False)
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self.value = nn.Linear(n_embed, head_size, bias=False)
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self.register_buffer('tril', torch.tril(torch.ones(block_size, block_size)))
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self.dropout = nn.Dropout(dropout)
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def forward(self, x):
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B, T, C = x.shape
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K = self.key(x) # (B, T, C)
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Q = self.query(x) # (B, T, C)
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wei = Q @ K.transpose(-2,-1) * C**-0.5 # (B, T, C) @ (B, H, C) -> (B, T, T)
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wei = wei.masked_fill(self.tril[:T, :T] == 0, float('-inf'))
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wei = F.softmax(wei, dim=-1)
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wei = self.dropout(wei)
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V = self.value(x) # (B, T, C)
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out = wei @ V # (B, T, T) @ (B, T, C) -> (B, T, C)
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return out
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class MultiHeadAttention(nn.Module):
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"""a multi-head self attention layer"""
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def __init__(self, n_embed, n_heads, head_size, block_size, dropout):
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super().__init__()
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self.heads = nn.ModuleList([AttentionHead(n_embed, head_size, block_size, dropout) for _ in range(n_heads)])
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self.fc = nn.Linear(head_size * n_heads, n_embed)
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self.dropout = nn.Dropout(dropout)
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def forward(self, x):
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out = torch.cat([h(x) for h in self.heads], dim=-1) # (B, T, n_heads*C)
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out = self.fc(out) # (B, T, C)
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out = self.dropout(out)
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return out
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class FeedForward(nn.Module):
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def __init__(self, n_embed, n_hidden, dropout):
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super().__init__()
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self.net = nn.Sequential(
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nn.Linear(n_embed, n_hidden),
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nn.ReLU(),
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nn.Linear(n_hidden, n_embed),
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nn.Dropout(dropout)
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)
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def forward(self, x):
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return self.net(x)
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class Block(nn.Module):
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def __init__(self, n_embed, n_heads, block_size, dropout):
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super().__init__()
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self.sa_heads = MultiHeadAttention(n_embed, n_heads, n_embed // n_heads, block_size, dropout)
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self.ffwd = FeedForward(n_embed, n_embed*4, dropout)
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self.ln1 = nn.LayerNorm(n_embed)
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self.ln2 = nn.LayerNorm(n_embed)
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def forward(self, x):
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x = x + self.sa_heads(self.ln1(x)) # [batch_size, block_size, n_embed]
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x = x + self.ffwd(self.ln2(x)) # [batch_size, block_size, n_embed]
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return x
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class NanoGPT(nn.Module):
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def __init__(self, hyperparameters, device="cpu"):
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super().__init__()
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# hyperparameters
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vocab_size = hyperparameters['vocab_size']
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block_size = hyperparameters['block_size']
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n_embed = hyperparameters['n_embed']
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n_heads = hyperparameters['n_heads']
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n_layers = hyperparameters['n_layers']
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dropout = hyperparameters['dropout']
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self.token_embedding_table = nn.Embedding(vocab_size, n_embed)
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self.position_embedding_table = nn.Embedding(block_size, n_embed)
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self.blocks = nn.Sequential(*[Block(n_embed, n_heads, block_size, dropout) for _ in range(n_layers)])
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self.ln_f = nn.LayerNorm(n_embed)
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self.lm_head = nn.Linear(n_embed, vocab_size)
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self.device = device
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self.block_size = block_size
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def forward(self, idx, targets=None):
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# idx and target are both [batch_size, block_size]
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B, T = idx.shape
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tok_emb = self.token_embedding_table(idx) # [batch_size, block_size, n_embed]
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pos_emb = self.position_embedding_table(torch.arange(T, device=self.device)) # [block_size, n_embed]
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x = tok_emb + pos_emb # [batch_size, block_size, n_embed]
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x = self.blocks(x)
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x = self.ln_f(x)
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logits = self.lm_head(x) # [batch_size, block_size, vocab_size]
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if targets is None:
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loss = None
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else:
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B, T, C = logits.shape
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logits = logits.view(B*T, C)
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targets = targets.view(B*T)
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loss = F.cross_entropy(logits, targets)
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return logits, loss
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# return 0, 0
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def generate(self, idx, max_new_tokens=100):
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# idx is (B, T)
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for _ in range(max_new_tokens):
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# get the last block_size tokens
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idx_cond = idx[:, -self.block_size:] # (B, T)
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# get the predictions
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logits, _ = self(idx_cond)
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# focus only on the last time step
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logits = logits[:, -1, :] # becomes (B, C)
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# apply softmax to get probabilities
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probs = F.softmax(logits, dim=1) # (B, C)
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# sample from the distribution
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idx_next = torch.multinomial(probs, num_samples=1) # (B, 1)
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# append sampled index to the running sequence
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idx = torch.cat((idx, idx_next), dim=1) # (B, T+1)
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return idx
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