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""" Position Embedding Utilities
Hacked together by / Copyright 2022 Ross Wightman
"""
import logging
import math
from typing import List, Tuple, Optional, Union
import torch
import torch.nn.functional as F
from .helpers import to_2tuple
_logger = logging.getLogger(__name__)
def resample_abs_pos_embed(
posemb,
new_size: List[int],
old_size: Optional[List[int]] = None,
num_prefix_tokens: int = 1,
interpolation: str = 'bicubic',
antialias: bool = True,
verbose: bool = False,
):
# sort out sizes, assume square if old size not provided
num_pos_tokens = posemb.shape[1]
num_new_tokens = new_size[0] * new_size[1] + num_prefix_tokens
if num_new_tokens == num_pos_tokens and new_size[0] == new_size[1]:
return posemb
if old_size is None:
hw = int(math.sqrt(num_pos_tokens - num_prefix_tokens))
old_size = hw, hw
if num_prefix_tokens:
posemb_prefix, posemb = posemb[:, :num_prefix_tokens], posemb[:, num_prefix_tokens:]
else:
posemb_prefix, posemb = None, posemb
# do the interpolation
embed_dim = posemb.shape[-1]
orig_dtype = posemb.dtype
posemb = posemb.float() # interpolate needs float32
posemb = posemb.reshape(1, old_size[0], old_size[1], -1).permute(0, 3, 1, 2)
posemb = F.interpolate(posemb, size=new_size, mode=interpolation, antialias=antialias)
posemb = posemb.permute(0, 2, 3, 1).reshape(1, -1, embed_dim)
posemb = posemb.to(orig_dtype)
# add back extra (class, etc) prefix tokens
if posemb_prefix is not None:
posemb = torch.cat([posemb_prefix, posemb], dim=1)
if not torch.jit.is_scripting() and verbose:
_logger.info(f'Resized position embedding: {old_size} to {new_size}.')
return posemb
def resample_abs_pos_embed_nhwc(
posemb,
new_size: List[int],
interpolation: str = 'bicubic',
antialias: bool = True,
verbose: bool = False,
):
if new_size[0] == posemb.shape[-3] and new_size[1] == posemb.shape[-2]:
return posemb
orig_dtype = posemb.dtype
posemb = posemb.float()
# do the interpolation
posemb = posemb.reshape(1, posemb.shape[-3], posemb.shape[-2], posemb.shape[-1]).permute(0, 3, 1, 2)
posemb = F.interpolate(posemb, size=new_size, mode=interpolation, antialias=antialias)
posemb = posemb.permute(0, 2, 3, 1).to(orig_dtype)
if not torch.jit.is_scripting() and verbose:
_logger.info(f'Resized position embedding: {posemb.shape[-3:-1]} to {new_size}.')
return posemb
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