First commit OCR_earsing and Synthetics Handwritten Recognition awesome repo

OCR_earsing/latent_diffusion/taming/modules/vqvae/quantize.py

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+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import numpy as np
+from torch import einsum
+from einops import rearrange
+
+
+class VectorQuantizer(nn.Module):
+    """
+    see https://github.com/MishaLaskin/vqvae/blob/d761a999e2267766400dc646d82d3ac3657771d4/models/quantizer.py
+    ____________________________________________
+    Discretization bottleneck part of the VQ-VAE.
+    Inputs:
+    - n_e : number of embeddings
+    - e_dim : dimension of embedding
+    - beta : commitment cost used in loss term, beta * ||z_e(x)-sg[e]||^2
+    _____________________________________________
+    """
+
+    # NOTE: this class contains a bug regarding beta; see VectorQuantizer2 for
+    # a fix and use legacy=False to apply that fix. VectorQuantizer2 can be
+    # used wherever VectorQuantizer has been used before and is additionally
+    # more efficient.
+    def __init__(self, n_e, e_dim, beta):
+        super(VectorQuantizer, self).__init__()
+        self.n_e = n_e
+        self.e_dim = e_dim
+        self.beta = beta
+
+        self.embedding = nn.Embedding(self.n_e, self.e_dim)
+        self.embedding.weight.data.uniform_(-1.0 / self.n_e, 1.0 / self.n_e)
+
+    def forward(self, z):
+        """
+        Inputs the output of the encoder network z and maps it to a discrete
+        one-hot vector that is the index of the closest embedding vector e_j
+        z (continuous) -> z_q (discrete)
+        z.shape = (batch, channel, height, width)
+        quantization pipeline:
+            1. get encoder input (B,C,H,W)
+            2. flatten input to (B*H*W,C)
+        """
+        # reshape z -> (batch, height, width, channel) and flatten
+        z = z.permute(0, 2, 3, 1).contiguous()
+        z_flattened = z.view(-1, self.e_dim)
+        # distances from z to embeddings e_j (z - e)^2 = z^2 + e^2 - 2 e * z
+
+        d = torch.sum(z_flattened ** 2, dim=1, keepdim=True) + \
+            torch.sum(self.embedding.weight**2, dim=1) - 2 * \
+            torch.matmul(z_flattened, self.embedding.weight.t())
+
+        ## could possible replace this here
+        # #\start...
+        # find closest encodings
+        min_encoding_indices = torch.argmin(d, dim=1).unsqueeze(1)
+
+        min_encodings = torch.zeros(
+            min_encoding_indices.shape[0], self.n_e).to(z)
+        min_encodings.scatter_(1, min_encoding_indices, 1)
+
+        # dtype min encodings: torch.float32
+        # min_encodings shape: torch.Size([2048, 512])
+        # min_encoding_indices.shape: torch.Size([2048, 1])
+
+        # get quantized latent vectors
+        z_q = torch.matmul(min_encodings, self.embedding.weight).view(z.shape)
+        #.........\end
+
+        # with:
+        # .........\start
+        #min_encoding_indices = torch.argmin(d, dim=1)
+        #z_q = self.embedding(min_encoding_indices)
+        # ......\end......... (TODO)
+
+        # compute loss for embedding
+        loss = torch.mean((z_q.detach()-z)**2) + self.beta * \
+            torch.mean((z_q - z.detach()) ** 2)
+
+        # preserve gradients
+        z_q = z + (z_q - z).detach()
+
+        # perplexity
+        e_mean = torch.mean(min_encodings, dim=0)
+        perplexity = torch.exp(-torch.sum(e_mean * torch.log(e_mean + 1e-10)))
+
+        # reshape back to match original input shape
+        z_q = z_q.permute(0, 3, 1, 2).contiguous()
+
+        return z_q, loss, (perplexity, min_encodings, min_encoding_indices)
+
+    def get_codebook_entry(self, indices, shape):
+        # shape specifying (batch, height, width, channel)
+        # TODO: check for more easy handling with nn.Embedding
+        min_encodings = torch.zeros(indices.shape[0], self.n_e).to(indices)
+        min_encodings.scatter_(1, indices[:,None], 1)
+
+        # get quantized latent vectors
+        z_q = torch.matmul(min_encodings.float(), self.embedding.weight)
+
+        if shape is not None:
+            z_q = z_q.view(shape)
+
+            # reshape back to match original input shape
+            z_q = z_q.permute(0, 3, 1, 2).contiguous()
+
+        return z_q
+
+
+class GumbelQuantize(nn.Module):
+    """
+    credit to @karpathy: https://github.com/karpathy/deep-vector-quantization/blob/main/model.py (thanks!)
+    Gumbel Softmax trick quantizer
+    Categorical Reparameterization with Gumbel-Softmax, Jang et al. 2016
+    https://arxiv.org/abs/1611.01144
+    """
+    def __init__(self, num_hiddens, embedding_dim, n_embed, straight_through=True,
+                 kl_weight=5e-4, temp_init=1.0, use_vqinterface=True,
+                 remap=None, unknown_index="random"):
+        super().__init__()
+
+        self.embedding_dim = embedding_dim
+        self.n_embed = n_embed
+
+        self.straight_through = straight_through
+        self.temperature = temp_init
+        self.kl_weight = kl_weight
+
+        self.proj = nn.Conv2d(num_hiddens, n_embed, 1)
+        self.embed = nn.Embedding(n_embed, embedding_dim)
+
+        self.use_vqinterface = use_vqinterface
+
+        self.remap = remap
+        if self.remap is not None:
+            self.register_buffer("used", torch.tensor(np.load(self.remap)))
+            self.re_embed = self.used.shape[0]
+            self.unknown_index = unknown_index # "random" or "extra" or integer
+            if self.unknown_index == "extra":
+                self.unknown_index = self.re_embed
+                self.re_embed = self.re_embed+1
+            print(f"Remapping {self.n_embed} indices to {self.re_embed} indices. "
+                  f"Using {self.unknown_index} for unknown indices.")
+        else:
+            self.re_embed = n_embed
+
+    def remap_to_used(self, inds):
+        ishape = inds.shape
+        assert len(ishape)>1
+        inds = inds.reshape(ishape[0],-1)
+        used = self.used.to(inds)
+        match = (inds[:,:,None]==used[None,None,...]).long()
+        new = match.argmax(-1)
+        unknown = match.sum(2)<1
+        if self.unknown_index == "random":
+            new[unknown]=torch.randint(0,self.re_embed,size=new[unknown].shape).to(device=new.device)
+        else:
+            new[unknown] = self.unknown_index
+        return new.reshape(ishape)
+
+    def unmap_to_all(self, inds):
+        ishape = inds.shape
+        assert len(ishape)>1
+        inds = inds.reshape(ishape[0],-1)
+        used = self.used.to(inds)
+        if self.re_embed > self.used.shape[0]: # extra token
+            inds[inds>=self.used.shape[0]] = 0 # simply set to zero
+        back=torch.gather(used[None,:][inds.shape[0]*[0],:], 1, inds)
+        return back.reshape(ishape)
+
+    def forward(self, z, temp=None, return_logits=False):
+        # force hard = True when we are in eval mode, as we must quantize. actually, always true seems to work
+        hard = self.straight_through if self.training else True
+        temp = self.temperature if temp is None else temp
+
+        logits = self.proj(z)
+        if self.remap is not None:
+            # continue only with used logits
+            full_zeros = torch.zeros_like(logits)
+            logits = logits[:,self.used,...]
+
+        soft_one_hot = F.gumbel_softmax(logits, tau=temp, dim=1, hard=hard)
+        if self.remap is not None:
+            # go back to all entries but unused set to zero
+            full_zeros[:,self.used,...] = soft_one_hot
+            soft_one_hot = full_zeros
+        z_q = einsum('b n h w, n d -> b d h w', soft_one_hot, self.embed.weight)
+
+        # + kl divergence to the prior loss
+        qy = F.softmax(logits, dim=1)
+        diff = self.kl_weight * torch.sum(qy * torch.log(qy * self.n_embed + 1e-10), dim=1).mean()
+
+        ind = soft_one_hot.argmax(dim=1)
+        if self.remap is not None:
+            ind = self.remap_to_used(ind)
+        if self.use_vqinterface:
+            if return_logits:
+                return z_q, diff, (None, None, ind), logits
+            return z_q, diff, (None, None, ind)
+        return z_q, diff, ind
+
+    def get_codebook_entry(self, indices, shape):
+        b, h, w, c = shape
+        assert b*h*w == indices.shape[0]
+        indices = rearrange(indices, '(b h w) -> b h w', b=b, h=h, w=w)
+        if self.remap is not None:
+            indices = self.unmap_to_all(indices)
+        one_hot = F.one_hot(indices, num_classes=self.n_embed).permute(0, 3, 1, 2).float()
+        z_q = einsum('b n h w, n d -> b d h w', one_hot, self.embed.weight)
+        return z_q
+
+
+class VectorQuantizer2(nn.Module):
+    """
+    Improved version over VectorQuantizer, can be used as a drop-in replacement. Mostly
+    avoids costly matrix multiplications and allows for post-hoc remapping of indices.
+    """
+    # NOTE: due to a bug the beta term was applied to the wrong term. for
+    # backwards compatibility we use the buggy version by default, but you can
+    # specify legacy=False to fix it.
+    def __init__(self, n_e, e_dim, beta, remap=None, unknown_index="random",
+                 sane_index_shape=False, legacy=True):
+        super().__init__()
+        self.n_e = n_e
+        self.e_dim = e_dim
+        self.beta = beta
+        self.legacy = legacy
+
+        self.embedding = nn.Embedding(self.n_e, self.e_dim)
+        self.embedding.weight.data.uniform_(-1.0 / self.n_e, 1.0 / self.n_e)
+
+        self.remap = remap
+        if self.remap is not None:
+            self.register_buffer("used", torch.tensor(np.load(self.remap)))
+            self.re_embed = self.used.shape[0]
+            self.unknown_index = unknown_index # "random" or "extra" or integer
+            if self.unknown_index == "extra":
+                self.unknown_index = self.re_embed
+                self.re_embed = self.re_embed+1
+            print(f"Remapping {self.n_e} indices to {self.re_embed} indices. "
+                  f"Using {self.unknown_index} for unknown indices.")
+        else:
+            self.re_embed = n_e
+
+        self.sane_index_shape = sane_index_shape
+
+    def remap_to_used(self, inds):
+        ishape = inds.shape
+        assert len(ishape)>1
+        inds = inds.reshape(ishape[0],-1)
+        used = self.used.to(inds)
+        match = (inds[:,:,None]==used[None,None,...]).long()
+        new = match.argmax(-1)
+        unknown = match.sum(2)<1
+        if self.unknown_index == "random":
+            new[unknown]=torch.randint(0,self.re_embed,size=new[unknown].shape).to(device=new.device)
+        else:
+            new[unknown] = self.unknown_index
+        return new.reshape(ishape)
+
+    def unmap_to_all(self, inds):
+        ishape = inds.shape
+        assert len(ishape)>1
+        inds = inds.reshape(ishape[0],-1)
+        used = self.used.to(inds)
+        if self.re_embed > self.used.shape[0]: # extra token
+            inds[inds>=self.used.shape[0]] = 0 # simply set to zero
+        back=torch.gather(used[None,:][inds.shape[0]*[0],:], 1, inds)
+        return back.reshape(ishape)
+
+    def forward(self, z, temp=None, rescale_logits=False, return_logits=False):
+        assert temp is None or temp==1.0, "Only for interface compatible with Gumbel"
+        assert rescale_logits==False, "Only for interface compatible with Gumbel"
+        assert return_logits==False, "Only for interface compatible with Gumbel"
+        # reshape z -> (batch, height, width, channel) and flatten
+        z = rearrange(z, 'b c h w -> b h w c').contiguous()
+        z_flattened = z.view(-1, self.e_dim)
+        # distances from z to embeddings e_j (z - e)^2 = z^2 + e^2 - 2 e * z
+
+        d = torch.sum(z_flattened ** 2, dim=1, keepdim=True) + \
+            torch.sum(self.embedding.weight**2, dim=1) - 2 * \
+            torch.einsum('bd,dn->bn', z_flattened, rearrange(self.embedding.weight, 'n d -> d n'))
+
+        min_encoding_indices = torch.argmin(d, dim=1)
+        z_q = self.embedding(min_encoding_indices).view(z.shape)
+        perplexity = None
+        min_encodings = None
+
+        # compute loss for embedding
+        if not self.legacy:
+            loss = self.beta * torch.mean((z_q.detach()-z)**2) + \
+                   torch.mean((z_q - z.detach()) ** 2)
+        else:
+            loss = torch.mean((z_q.detach()-z)**2) + self.beta * \
+                   torch.mean((z_q - z.detach()) ** 2)
+
+        # preserve gradients
+        z_q = z + (z_q - z).detach()
+
+        # reshape back to match original input shape
+        z_q = rearrange(z_q, 'b h w c -> b c h w').contiguous()
+
+        if self.remap is not None:
+            min_encoding_indices = min_encoding_indices.reshape(z.shape[0],-1) # add batch axis
+            min_encoding_indices = self.remap_to_used(min_encoding_indices)
+            min_encoding_indices = min_encoding_indices.reshape(-1,1) # flatten
+
+        if self.sane_index_shape:
+            min_encoding_indices = min_encoding_indices.reshape(
+                z_q.shape[0], z_q.shape[2], z_q.shape[3])
+
+        return z_q, loss, (perplexity, min_encodings, min_encoding_indices)
+
+    def get_codebook_entry(self, indices, shape):
+        # shape specifying (batch, height, width, channel)
+        if self.remap is not None:
+            indices = indices.reshape(shape[0],-1) # add batch axis
+            indices = self.unmap_to_all(indices)
+            indices = indices.reshape(-1) # flatten again
+
+        # get quantized latent vectors
+        z_q = self.embedding(indices)
+
+        if shape is not None:
+            z_q = z_q.view(shape)
+            # reshape back to match original input shape
+            z_q = z_q.permute(0, 3, 1, 2).contiguous()
+
+        return z_q
+
+class EmbeddingEMA(nn.Module):
+    def __init__(self, num_tokens, codebook_dim, decay=0.99, eps=1e-5):
+        super().__init__()
+        self.decay = decay
+        self.eps = eps        
+        weight = torch.randn(num_tokens, codebook_dim)
+        self.weight = nn.Parameter(weight, requires_grad = False)
+        self.cluster_size = nn.Parameter(torch.zeros(num_tokens), requires_grad = False)
+        self.embed_avg = nn.Parameter(weight.clone(), requires_grad = False)
+        self.update = True
+
+    def forward(self, embed_id):
+        return F.embedding(embed_id, self.weight)
+
+    def cluster_size_ema_update(self, new_cluster_size):
+        self.cluster_size.data.mul_(self.decay).add_(new_cluster_size, alpha=1 - self.decay)
+
+    def embed_avg_ema_update(self, new_embed_avg): 
+        self.embed_avg.data.mul_(self.decay).add_(new_embed_avg, alpha=1 - self.decay)
+
+    def weight_update(self, num_tokens):
+        n = self.cluster_size.sum()
+        smoothed_cluster_size = (
+                (self.cluster_size + self.eps) / (n + num_tokens * self.eps) * n
+            )
+        #normalize embedding average with smoothed cluster size
+        embed_normalized = self.embed_avg / smoothed_cluster_size.unsqueeze(1)
+        self.weight.data.copy_(embed_normalized)   
+
+
+class EMAVectorQuantizer(nn.Module):
+    def __init__(self, n_embed, embedding_dim, beta, decay=0.99, eps=1e-5,
+                remap=None, unknown_index="random"):
+        super().__init__()
+        self.codebook_dim = codebook_dim
+        self.num_tokens = num_tokens
+        self.beta = beta
+        self.embedding = EmbeddingEMA(self.num_tokens, self.codebook_dim, decay, eps)
+
+        self.remap = remap
+        if self.remap is not None:
+            self.register_buffer("used", torch.tensor(np.load(self.remap)))
+            self.re_embed = self.used.shape[0]
+            self.unknown_index = unknown_index # "random" or "extra" or integer
+            if self.unknown_index == "extra":
+                self.unknown_index = self.re_embed
+                self.re_embed = self.re_embed+1
+            print(f"Remapping {self.n_embed} indices to {self.re_embed} indices. "
+                  f"Using {self.unknown_index} for unknown indices.")
+        else:
+            self.re_embed = n_embed
+
+    def remap_to_used(self, inds):
+        ishape = inds.shape
+        assert len(ishape)>1
+        inds = inds.reshape(ishape[0],-1)
+        used = self.used.to(inds)
+        match = (inds[:,:,None]==used[None,None,...]).long()
+        new = match.argmax(-1)
+        unknown = match.sum(2)<1
+        if self.unknown_index == "random":
+            new[unknown]=torch.randint(0,self.re_embed,size=new[unknown].shape).to(device=new.device)
+        else:
+            new[unknown] = self.unknown_index
+        return new.reshape(ishape)
+
+    def unmap_to_all(self, inds):
+        ishape = inds.shape
+        assert len(ishape)>1
+        inds = inds.reshape(ishape[0],-1)
+        used = self.used.to(inds)
+        if self.re_embed > self.used.shape[0]: # extra token
+            inds[inds>=self.used.shape[0]] = 0 # simply set to zero
+        back=torch.gather(used[None,:][inds.shape[0]*[0],:], 1, inds)
+        return back.reshape(ishape)
+
+    def forward(self, z):
+        # reshape z -> (batch, height, width, channel) and flatten
+        #z, 'b c h w -> b h w c'
+        z = rearrange(z, 'b c h w -> b h w c')
+        z_flattened = z.reshape(-1, self.codebook_dim)
+        
+        # distances from z to embeddings e_j (z - e)^2 = z^2 + e^2 - 2 e * z
+        d = z_flattened.pow(2).sum(dim=1, keepdim=True) + \
+            self.embedding.weight.pow(2).sum(dim=1) - 2 * \
+            torch.einsum('bd,nd->bn', z_flattened, self.embedding.weight) # 'n d -> d n'
+
+
+        encoding_indices = torch.argmin(d, dim=1)
+
+        z_q = self.embedding(encoding_indices).view(z.shape)
+        encodings = F.one_hot(encoding_indices, self.num_tokens).type(z.dtype)     
+        avg_probs = torch.mean(encodings, dim=0)
+        perplexity = torch.exp(-torch.sum(avg_probs * torch.log(avg_probs + 1e-10)))
+
+        if self.training and self.embedding.update:
+            #EMA cluster size
+            encodings_sum = encodings.sum(0)            
+            self.embedding.cluster_size_ema_update(encodings_sum)
+            #EMA embedding average
+            embed_sum = encodings.transpose(0,1) @ z_flattened            
+            self.embedding.embed_avg_ema_update(embed_sum)
+            #normalize embed_avg and update weight
+            self.embedding.weight_update(self.num_tokens)
+
+        # compute loss for embedding
+        loss = self.beta * F.mse_loss(z_q.detach(), z) 
+
+        # preserve gradients
+        z_q = z + (z_q - z).detach()
+
+        # reshape back to match original input shape
+        #z_q, 'b h w c -> b c h w'
+        z_q = rearrange(z_q, 'b h w c -> b c h w')
+        return z_q, loss, (perplexity, encodings, encoding_indices)