models/scnet_unofficial/utils.py

from typing import List, Tuple, Union

import torch


def create_intervals(
    splits: List[Union[float, int]],
) -> List[Union[Tuple[float, float], Tuple[int, int]]]:
    start = 0
    return [(start, start := start + split) for split in splits]


def get_conv_output_shape(
    input_shape: int,
    kernel_size: int = 1,
    padding: int = 0,
    dilation: int = 1,
    stride: int = 1,
) -> int:
    return int(
        (input_shape + 2 * padding - dilation * (kernel_size - 1) - 1) / stride + 1
    )


def get_convtranspose_output_padding(
    input_shape: int,
    output_shape: int,
    kernel_size: int = 1,
    padding: int = 0,
    dilation: int = 1,
    stride: int = 1,
) -> int:
    return (
        output_shape
        - (input_shape - 1) * stride
        + 2 * padding
        - dilation * (kernel_size - 1)
        - 1
    )


def compute_sd_layer_shapes(
    input_shape: int,
    bandsplit_ratios: List[float],
    downsample_strides: List[int],
    n_layers: int,
) -> Tuple[List[List[int]], List[List[Tuple[int, int]]]]:
    bandsplit_shapes_list = []
    conv2d_shapes_list = []
    for _ in range(n_layers):
        bandsplit_intervals = create_intervals(bandsplit_ratios)
        bandsplit_shapes = [
            int(right * input_shape) - int(left * input_shape)
            for left, right in bandsplit_intervals
        ]
        conv2d_shapes = [
            get_conv_output_shape(bs, stride=ds)
            for bs, ds in zip(bandsplit_shapes, downsample_strides)
        ]
        input_shape = sum(conv2d_shapes)
        bandsplit_shapes_list.append(bandsplit_shapes)
        conv2d_shapes_list.append(create_intervals(conv2d_shapes))

    return bandsplit_shapes_list, conv2d_shapes_list


def compute_gcr(subband_shapes: List[List[int]]) -> float:
    t = torch.Tensor(subband_shapes)
    gcr = torch.stack(
        [(1 - t[i + 1] / t[i]).mean() for i in range(0, len(t) - 1)]
    ).mean()
    return float(gcr)