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import torch
import torch.nn as nn
import numpy as np
approx_gelu = lambda: nn.GELU(approximate="tanh")
def get_layernorm(hidden_size: torch.Tensor, eps: float, affine: bool, use_kernel: bool):
if use_kernel:
try:
from apex.normalization import FusedLayerNorm
return FusedLayerNorm(hidden_size, elementwise_affine=affine, eps=eps)
except ImportError:
raise RuntimeError("FusedLayerNorm not available. Please install apex.")
else:
return nn.LayerNorm(hidden_size, eps, elementwise_affine=affine)
def get_1d_sincos_pos_embed(embed_dim, length, scale=1.0):
pos = np.arange(0, length)[..., None] / scale
return get_1d_sincos_pos_embed_from_grid(embed_dim, pos)
def get_1d_sincos_pos_embed_from_grid(embed_dim, pos):
"""
embed_dim: output dimension for each position
pos: a list of positions to be encoded: size (M,)
out: (M, D)
"""
assert embed_dim % 2 == 0
omega = np.arange(embed_dim // 2, dtype=np.float64)
omega /= embed_dim / 2.0
omega = 1.0 / 10000**omega # (D/2,)
pos = pos.reshape(-1) # (M,)
out = np.einsum("m,d->md", pos, omega) # (M, D/2), outer product
emb_sin = np.sin(out) # (M, D/2)
emb_cos = np.cos(out) # (M, D/2)
emb = np.concatenate([emb_sin, emb_cos], axis=1) # (M, D)
return emb
def get_2d_sincos_pos_embed(embed_dim, grid_size, cls_token=False, extra_tokens=0, scale=1.0, base_size=None):
"""
grid_size: int of the grid height and width
return:
pos_embed: [grid_size*grid_size, embed_dim] or [1+grid_size*grid_size, embed_dim] (w/ or w/o cls_token)
"""
if not isinstance(grid_size, tuple):
grid_size = (grid_size, grid_size)
grid_h = np.arange(grid_size[0], dtype=np.float32) / scale
grid_w = np.arange(grid_size[1], dtype=np.float32) / scale
if base_size is not None:
grid_h *= base_size / grid_size[0]
grid_w *= base_size / grid_size[1]
grid = np.meshgrid(grid_w, grid_h) # here w goes first
grid = np.stack(grid, axis=0)
grid = grid.reshape([2, 1, grid_size[1], grid_size[0]])
pos_embed = get_2d_sincos_pos_embed_from_grid(embed_dim, grid)
if cls_token and extra_tokens > 0:
pos_embed = np.concatenate([np.zeros([extra_tokens, embed_dim]), pos_embed], axis=0)
return pos_embed
def get_2d_sincos_pos_embed_from_grid(embed_dim, grid):
assert embed_dim % 2 == 0
# use half of dimensions to encode grid_h
emb_h = get_1d_sincos_pos_embed_from_grid(embed_dim // 2, grid[0]) # (H*W, D/2)
emb_w = get_1d_sincos_pos_embed_from_grid(embed_dim // 2, grid[1]) # (H*W, D/2)
emb = np.concatenate([emb_h, emb_w], axis=1) # (H*W, D)
return emb
def t2i_modulate(x, shift, scale):
return x * (1 + scale) + shift
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