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# EfficientViT: Multi-Scale Linear Attention for High-Resolution Dense Prediction | |
# Han Cai, Junyan Li, Muyan Hu, Chuang Gan, Song Han | |
# International Conference on Computer Vision (ICCV), 2023 | |
import torch | |
import torch.nn as nn | |
from torch.nn.modules.batchnorm import _BatchNorm | |
__all__ = ["init_modules", "zero_last_gamma"] | |
def init_modules(model: nn.Module or list[nn.Module], init_type="trunc_normal") -> None: | |
_DEFAULT_INIT_PARAM = {"trunc_normal": 0.02} | |
if isinstance(model, list): | |
for sub_module in model: | |
init_modules(sub_module, init_type) | |
else: | |
init_params = init_type.split("@") | |
init_params = float(init_params[1]) if len(init_params) > 1 else None | |
if init_type.startswith("trunc_normal"): | |
init_func = lambda param: nn.init.trunc_normal_( | |
param, std=(init_params or _DEFAULT_INIT_PARAM["trunc_normal"]) | |
) | |
else: | |
raise NotImplementedError | |
for m in model.modules(): | |
if isinstance(m, (nn.Conv2d, nn.Linear, nn.ConvTranspose2d)): | |
init_func(m.weight) | |
if m.bias is not None: | |
m.bias.data.zero_() | |
elif isinstance(m, nn.Embedding): | |
init_func(m.weight) | |
elif isinstance(m, (_BatchNorm, nn.GroupNorm, nn.LayerNorm)): | |
m.weight.data.fill_(1) | |
m.bias.data.zero_() | |
else: | |
weight = getattr(m, "weight", None) | |
bias = getattr(m, "bias", None) | |
if isinstance(weight, torch.nn.Parameter): | |
init_func(weight) | |
if isinstance(bias, torch.nn.Parameter): | |
bias.data.zero_() | |
def zero_last_gamma(model: nn.Module, init_val=0) -> None: | |
import efficientvit.models.nn.ops as ops | |
for m in model.modules(): | |
if isinstance(m, ops.ResidualBlock) and isinstance( | |
m.shortcut, ops.IdentityLayer | |
): | |
if isinstance(m.main, (ops.DSConv, ops.MBConv, ops.FusedMBConv)): | |
parent_module = m.main.point_conv | |
elif isinstance(m.main, ops.ResBlock): | |
parent_module = m.main.conv2 | |
elif isinstance(m.main, ops.ConvLayer): | |
parent_module = m.main | |
elif isinstance(m.main, (ops.LiteMLA)): | |
parent_module = m.main.proj | |
else: | |
parent_module = None | |
if parent_module is not None: | |
norm = getattr(parent_module, "norm", None) | |
if norm is not None: | |
nn.init.constant_(norm.weight, init_val) | |