| # SPDX-License-Identifier: MPL-2.0 |
| # Copyright (c) 2022 Philipp Le <philipp@philipple.de>. |
| # This Source Code Form is subject to the terms of the Mozilla Public |
| # License, v. 2.0. If a copy of the MPL was not distributed with this |
| # file, You can obtain one at https://mozilla.org/MPL/2.0/. |
| |
| import numpy as np |
| |
| |
| def swap_freq(x: np.ndarray, axis: int = 0) -> np.ndarray: |
| transposed = np.swapaxes(x, 0, axis) |
| swapped = np.zeros(transposed.shape, dtype=np.complex128) |
| length = transposed.shape[0] |
| swapped[int(length/2):, ] = transposed[:int(length/2), ] |
| swapped[:int(length/2), ] = transposed[int(length/2):, ] |
| return np.swapaxes(swapped, axis, 0) |
| |
| |
| def abs_log_fft(x: np.ndarray, factor: float = 20, axis: int = 0) -> np.ndarray: |
| return factor * np.log10(np.abs(swap_freq(np.fft.fft(x), axis)) / len(x)) |