update readme

model/blocks.py

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+import math, pdb
+from abc import abstractmethod
+from dataclasses import dataclass
+from numbers import Number
+
+import torch as th
+import torch.nn.functional as F
+from choices import *
+from config_base import BaseConfig
+from torch import nn
+import numpy as np
+from .nn import (avg_pool_nd, conv_nd, linear, normalization,
+                 timestep_embedding, zero_module)
+                                                                  
+                                                  
+class TimestepBlock(nn.Module):
+    """
+    Any module where forward() takes timestep embeddings as a second argument.
+    """
+    @abstractmethod
+    def forward(self, x, emb=None, cond=None, lateral=None):
+        """
+        Apply the module to `x` given `emb` timestep embeddings.
+        """
+
+        
+class TimestepEmbedSequential(nn.Sequential, TimestepBlock):
+    """
+    A sequential module that passes timestep embeddings to the children that
+    support it as an extra input.
+    """
+    def forward(self, x, emb=None, cond=None, lateral=None):
+        for layer in self:
+            if isinstance(layer, TimestepBlock):
+                '''if layer(x, emb=emb, cond=cond, lateral=lateral).shape[-1]==10:
+                    pdb.set_trace()'''
+                x = layer(x, emb=emb, cond=cond, lateral=lateral)
+            else:
+                '''if layer(x).shape[-1]==10:
+                    pdb.set_trace()'''
+                x = layer(x)
+        return x
+
+
+@dataclass
+class ResBlockConfig(BaseConfig):
+    channels: int
+    emb_channels: int
+    dropout: float
+    out_channels: int = None
+    # condition the resblock with time (and encoder's output)
+    use_condition: bool = True
+    # whether to use 3x3 conv for skip path when the channels aren't matched
+    use_conv: bool = False
+    # dimension of conv (always 1 = 1d)
+    dims: int = 1
+    up: bool = False
+    down: bool = False
+    # whether to condition with both time & encoder's output
+    two_cond: bool = False
+    # number of encoders' output channels
+    cond_emb_channels: int = None
+    # suggest: False
+    has_lateral: bool = False
+    lateral_channels: int = None
+    # whether to init the convolution with zero weights
+    # this is default from BeatGANs and seems to help learning
+    use_zero_module: bool = True
+
+    def __post_init__(self):
+        self.out_channels = self.out_channels or self.channels
+        self.cond_emb_channels = self.cond_emb_channels or self.emb_channels
+
+    def make_model(self):
+        return ResBlock(self)
+      
+      
+class ResBlock(TimestepBlock):
+    """
+    A residual block that can optionally change the number of channels.
+
+    total layers:
+        in_layers
+        - norm
+        - act
+        - conv
+        out_layers
+        - norm
+        - (modulation)
+        - act
+        - conv
+    """
+    def __init__(self, conf: ResBlockConfig):
+        super().__init__()
+        self.conf = conf
+        
+        #############################
+        # IN LAYERS
+        #############################
+        assert conf.lateral_channels is None
+        layers = [
+            normalization(conf.channels),
+            nn.SiLU(),
+            conv_nd(conf.dims, conf.channels, conf.out_channels, 3, padding=1) ## 3 is kernel size
+        ]
+        self.in_layers = nn.Sequential(*layers)
+
+        self.updown = conf.up or conf.down
+
+        if conf.up:
+            self.h_upd = Upsample(conf.channels, False, conf.dims)
+            self.x_upd = Upsample(conf.channels, False, conf.dims)
+        elif conf.down:
+            self.h_upd = Downsample(conf.channels, False, conf.dims)
+            self.x_upd = Downsample(conf.channels, False, conf.dims)
+        else:
+            self.h_upd = self.x_upd = nn.Identity()
+
+        #############################
+        # OUT LAYERS CONDITIONS
+        #############################
+        if conf.use_condition:
+            # condition layers for the out_layers
+            self.emb_layers = nn.Sequential(
+                nn.SiLU(),
+                linear(conf.emb_channels, 2 * conf.out_channels),
+            )
+
+            if conf.two_cond:
+                self.cond_emb_layers = nn.Sequential(
+                    nn.SiLU(),
+                    linear(conf.cond_emb_channels, conf.out_channels),
+                )
+            #############################
+            # OUT LAYERS (ignored when there is no condition)
+            #############################
+            # original version
+            conv = conv_nd(conf.dims,
+                           conf.out_channels,
+                           conf.out_channels,
+                           3,
+                           padding=1)
+            if conf.use_zero_module:
+                # zere out the weights
+                # it seems to help training
+                conv = zero_module(conv)
+
+            # construct the layers
+            # - norm
+            # - (modulation)
+            # - act
+            # - dropout
+            # - conv
+            layers = []
+            layers += [
+                normalization(conf.out_channels),
+                nn.SiLU(),
+                nn.Dropout(p=conf.dropout),
+                conv,
+            ]
+            self.out_layers = nn.Sequential(*layers)
+
+        #############################
+        # SKIP LAYERS
+        #############################
+        if conf.out_channels == conf.channels:
+            # cannot be used with gatedconv, also gatedconv is alsways used as the first block
+            self.skip_connection = nn.Identity()
+        else:
+            if conf.use_conv:
+                kernel_size = 3
+                padding = 1
+            else:
+                kernel_size = 1
+                padding = 0
+
+            self.skip_connection = conv_nd(conf.dims,
+                                           conf.channels,
+                                           conf.out_channels,
+                                           kernel_size,
+                                           padding=padding)
+
+    def forward(self, x, emb=None, cond=None, lateral=None):
+        """
+        Apply the block to a Tensor, conditioned on a timestep embedding.
+
+        Args:
+            x: input
+            lateral: lateral connection from the encoder
+        """
+        return self._forward(x, emb, cond, lateral)
+
+    def _forward(
+        self,
+        x,
+        emb=None,
+        cond=None,
+        lateral=None,
+    ):
+        """
+        Args:
+            lateral: required if "has_lateral" and non-gated, with gated, it can be supplied optionally    
+        """
+        if self.conf.has_lateral:
+            # lateral may be supplied even if it doesn't require
+            # the model will take the lateral only if "has_lateral"
+            assert lateral is not None
+            # x = F.interpolate(x, size=(lateral.size(2)), mode='linear' )
+            x = th.cat([x, lateral], dim=1)
+
+        if self.updown:
+            in_rest, in_conv = self.in_layers[:-1], self.in_layers[-1]
+            h = in_rest(x)
+            h = self.h_upd(h)
+            x = self.x_upd(x)
+            h = in_conv(h)
+        else:
+            h = self.in_layers(x)
+
+        if self.conf.use_condition:
+            # it's possible that the network may not receieve the time emb
+            # this happens with autoenc and setting the time_at
+            if emb is not None:
+                emb_out = self.emb_layers(emb).type(h.dtype)
+            else:
+                emb_out = None
+                
+            if self.conf.two_cond:
+                # it's possible that the network is two_cond
+                # but it doesn't get the second condition
+                # in which case, we ignore the second condition
+                # and treat as if the network has one condition
+                if cond is None:
+                    cond_out = None
+                else:
+                    if not isinstance(cond, th.Tensor):
+                        assert isinstance(cond, dict)
+                        cond = cond['cond']                    
+                    cond_out = self.cond_emb_layers(cond).type(h.dtype)
+                if cond_out is not None:
+                    while len(cond_out.shape) < len(h.shape):
+                        cond_out = cond_out[..., None]
+            else:
+                cond_out = None
+
+            # this is the new refactored code
+            h = apply_conditions(
+                h=h,
+                emb=emb_out,
+                cond=cond_out,
+                layers=self.out_layers,
+                scale_bias=1,
+                in_channels=self.conf.out_channels,
+                up_down_layer=None,
+            )
+
+        return self.skip_connection(x) + h
+
+
+def apply_conditions(
+    h,
+    emb=None,
+    cond=None,
+    layers: nn.Sequential = None,
+    scale_bias: float = 1,
+    in_channels: int = 512,
+    up_down_layer: nn.Module = None,
+):
+    """
+    apply conditions on the feature maps
+
+    Args:
+        emb: time conditional (ready to scale + shift)
+        cond: encoder's conditional (ready to scale + shift)
+    """
+    two_cond = emb is not None and cond is not None
+
+    if emb is not None:
+        # adjusting shapes
+        while len(emb.shape) < len(h.shape):            
+            emb = emb[..., None]            
+            
+    if two_cond:
+        # adjusting shapes        
+        while len(cond.shape) < len(h.shape):            
+            cond = cond[..., None]            
+        # time first
+        scale_shifts = [emb, cond]
+    else:
+        # "cond" is not used with single cond mode
+        scale_shifts = [emb]
+
+    # support scale, shift or shift only
+    for i, each in enumerate(scale_shifts):
+        if each is None:
+            # special case: the condition is not provided
+            a = None
+            b = None
+        else:
+            if each.shape[1] == in_channels * 2:
+                a, b = th.chunk(each, 2, dim=1)
+            else:
+                a = each
+                b = None
+        scale_shifts[i] = (a, b)
+
+    # condition scale bias could be a list
+    if isinstance(scale_bias, Number):
+        biases = [scale_bias] * len(scale_shifts)
+    else:
+        # a list
+        biases = scale_bias
+
+    # default, the scale & shift are applied after the group norm but BEFORE SiLU
+    pre_layers, post_layers = layers[0], layers[1:]
+
+    # spilt the post layer to be able to scale up or down before conv
+    # post layers will contain only the conv
+    mid_layers, post_layers = post_layers[:-2], post_layers[-2:]
+
+    h = pre_layers(h)
+    # scale and shift for each condition
+    for i, (scale, shift) in enumerate(scale_shifts):
+        # if scale is None, it indicates that the condition is not provided
+        if scale is not None:                        
+            h = h * (biases[i] + scale)
+            if shift is not None:
+                h = h + shift
+    h = mid_layers(h)
+
+    # upscale or downscale if any just before the last conv
+    if up_down_layer is not None:
+        h = up_down_layer(h)
+    h = post_layers(h)
+    return h
+
+
+class Upsample(nn.Module):
+    """
+    An upsampling layer with an optional convolution.
+
+    :param channels: channels in the inputs and outputs.
+    :param use_conv: a bool determining if a convolution is applied.
+    :param dims: determines if the signal is 1D, 2D, or 3D. If 3D, then
+                 upsampling occurs in the inner-two dimensions.
+    """
+    def __init__(self, channels, use_conv, dims=2, out_channels=None):
+        super().__init__()
+        self.channels = channels
+        self.out_channels = out_channels or channels
+        self.use_conv = use_conv
+        self.dims = dims
+        if use_conv:
+            self.conv = conv_nd(dims,
+                                self.channels,
+                                self.out_channels,
+                                3,
+                                padding=1)
+
+    def forward(self, x):
+        assert x.shape[1] == self.channels
+        if self.dims == 3:
+            x = F.interpolate(x, (x.shape[2], x.shape[3] * 2, x.shape[4] * 2),
+                              mode="nearest")
+        else:
+            # if x.shape[2] == 4:
+            #     feature = 9
+            #     x = F.interpolate(x, size=(feature), mode="nearest")
+            # if x.shape[2] == 8:
+            #     feature = 9
+            #     x = F.interpolate(x, size=(feature), mode="nearest")
+            # else:
+            x = F.interpolate(x, scale_factor=2, mode="nearest")
+        if self.use_conv:
+            x = self.conv(x)
+        return x
+
+
+class Downsample(nn.Module):
+    """
+    A downsampling layer with an optional convolution.
+
+    :param channels: channels in the inputs and outputs.
+    :param use_conv: a bool determining if a convolution is applied.
+    :param dims: determines if the signal is 1D, 2D, or 3D. If 3D, then
+                 downsampling occurs in the inner-two dimensions.
+    """
+    def __init__(self, channels, use_conv, dims=2, out_channels=None):
+        super().__init__()
+        self.channels = channels
+        self.out_channels = out_channels or channels
+        self.use_conv = use_conv
+        self.dims = dims
+        self.stride = 2 if dims != 3 else (1, 2, 2)
+        if use_conv:
+            self.op = conv_nd(dims,
+                              self.channels,
+                              self.out_channels,
+                              3,
+                              stride=self.stride,
+                              padding=1)
+        else:
+            assert self.channels == self.out_channels
+            self.op = avg_pool_nd(dims, kernel_size=self.stride, stride=self.stride)
+
+    def forward(self, x):
+        assert x.shape[1] == self.channels
+        # if x.shape[2] % 2 != 0:
+        #     op = avg_pool_nd(self.dims, kernel_size=3, stride=2)
+        #     return op(x)
+        # if x.shape[2] % 2 != 0:
+        #     op = avg_pool_nd(self.dims, kernel_size=2, stride=1)
+        #     return op(x)
+        # else: 
+        return self.op(x)
+
+        
+class AttentionBlock(nn.Module):
+    """
+    An attention block that allows spatial positions to attend to each other.
+
+    Originally ported from here, but adapted to the N-d case.
+    https://github.com/hojonathanho/diffusion/blob/1e0dceb3b3495bbe19116a5e1b3596cd0706c543/diffusion_tf/models/unet.py#L66.
+    """
+    def __init__(
+        self,
+        channels,
+        num_heads=1,
+        num_head_channels=-1,
+        use_new_attention_order=False,
+    ):
+        super().__init__()
+        self.channels = channels
+        if num_head_channels == -1:
+            self.num_heads = num_heads
+        else:
+            assert (
+                channels % num_head_channels == 0
+            ), f"q,k,v channels {channels} is not divisible by num_head_channels {num_head_channels}"
+            self.num_heads = channels // num_head_channels
+        self.norm = normalization(channels)
+        self.qkv = conv_nd(1, channels, channels * 3, 1)
+        if use_new_attention_order:
+            # split qkv before split heads
+            self.attention = QKVAttention(self.num_heads)
+        else:
+            # split heads before split qkv
+            self.attention = QKVAttentionLegacy(self.num_heads)
+
+        self.proj_out = zero_module(conv_nd(1, channels, channels, 1))
+
+    def forward(self, x):
+        return self._forward(x)
+
+    def _forward(self, x):
+        b, c, *spatial = x.shape
+        x = x.reshape(b, c, -1)
+        qkv = self.qkv(self.norm(x))
+        h = self.attention(qkv)
+        h = self.proj_out(h)
+        return (x + h).reshape(b, c, *spatial)
+
+
+def count_flops_attn(model, _x, y):
+    """
+    A counter for the `thop` package to count the operations in an
+    attention operation.
+    Meant to be used like:
+        macs, params = thop.profile(
+            model,
+            inputs=(inputs, timestamps),
+            custom_ops={QKVAttention: QKVAttention.count_flops},
+        )
+    """
+    b, c, *spatial = y[0].shape
+    num_spatial = int(np.prod(spatial))
+    # We perform two matmuls with the same number of ops.
+    # The first computes the weight matrix, the second computes
+    # the combination of the value vectors.
+    matmul_ops = 2 * b * (num_spatial**2) * c
+    model.total_ops += th.DoubleTensor([matmul_ops])
+
+
+class QKVAttentionLegacy(nn.Module):
+    """
+    A module which performs QKV attention. Matches legacy QKVAttention + input/ouput heads shaping
+    """
+    def __init__(self, n_heads):
+        super().__init__()
+        self.n_heads = n_heads
+
+    def forward(self, qkv):
+        """
+        Apply QKV attention.
+
+        :param qkv: an [N x (H * 3 * C) x T] tensor of Qs, Ks, and Vs.
+        :return: an [N x (H * C) x T] tensor after attention.
+        """
+        bs, width, length = qkv.shape
+        assert width % (3 * self.n_heads) == 0
+        ch = width // (3 * self.n_heads)
+        q, k, v = qkv.reshape(bs * self.n_heads, ch * 3, length).split(ch, dim=1)
+        scale = 1 / math.sqrt(math.sqrt(ch))
+        weight = th.einsum(
+            "bct,bcs->bts", q * scale,
+            k * scale)  # More stable with f16 than dividing afterwards
+        weight = th.softmax(weight.float(), dim=-1).type(weight.dtype)
+        a = th.einsum("bts,bcs->bct", weight, v)
+        return a.reshape(bs, -1, length)
+
+    @staticmethod
+    def count_flops(model, _x, y):
+        return count_flops_attn(model, _x, y)
+
+
+class QKVAttention(nn.Module):
+    """
+    A module which performs QKV attention and splits in a different order.
+    """
+    def __init__(self, n_heads):
+        super().__init__()
+        self.n_heads = n_heads
+
+    def forward(self, qkv):
+        """
+        Apply QKV attention.
+
+        :param qkv: an [N x (3 * H * C) x T] tensor of Qs, Ks, and Vs.
+        :return: an [N x (H * C) x T] tensor after attention.
+        """
+        bs, width, length = qkv.shape
+        pdb.set_trace()
+        assert width % (3 * self.n_heads) == 0
+        ch = width // (3 * self.n_heads)
+        q, k, v = qkv.chunk(3, dim=1)
+        scale = 1 / math.sqrt(math.sqrt(ch))
+        weight = th.einsum(
+            "bct,bcs->bts",
+            (q * scale).view(bs * self.n_heads, ch, length),
+            (k * scale).view(bs * self.n_heads, ch, length),
+        )  # More stable with f16 than dividing afterwards
+        weight = th.softmax(weight.float(), dim=-1).type(weight.dtype)
+        a = th.einsum("bts,bcs->bct", weight,
+                      v.reshape(bs * self.n_heads, ch, length))
+        return a.reshape(bs, -1, length)
+
+    @staticmethod
+    def count_flops(model, _x, y):
+        return count_flops_attn(model, _x, y)
+        
+        
+class AttentionPool2d(nn.Module):
+    """
+    Adapted from CLIP: https://github.com/openai/CLIP/blob/main/clip/model.py
+    """
+    def __init__(
+        self,
+        spacial_dim: int,
+        embed_dim: int,
+        num_heads_channels: int,
+        output_dim: int = None,
+    ):
+        super().__init__()
+        self.positional_embedding = nn.Parameter(
+            th.randn(embed_dim, spacial_dim**2 + 1) / embed_dim**0.5)
+        self.qkv_proj = conv_nd(1, embed_dim, 3 * embed_dim, 1)
+        self.c_proj = conv_nd(1, embed_dim, output_dim or embed_dim, 1)
+        self.num_heads = embed_dim // num_heads_channels
+        self.attention = QKVAttention(self.num_heads)
+
+    def forward(self, x):
+        b, c, *_spatial = x.shape
+        x = x.reshape(b, c, -1)  # NC(HW)
+        x = th.cat([x.mean(dim=-1, keepdim=True), x], dim=-1)  # NC(HW+1)
+        x = x + self.positional_embedding[None, :, :].to(x.dtype)  # NC(HW+1)
+        x = self.qkv_proj(x)
+        x = self.attention(x)
+        x = self.c_proj(x)
+        return x[:, :, 0]