import numpy as np from scipy.ndimage import measurements import scipy.fftpack as fft def shift_array(arr, dy, dx): temp = np.roll(arr, (dy, dx), (0, 1)) return temp def roll_to_pos(arr: np.ndarray, y: int = 0, x: int = 0, pos: tuple = None, move_maximum: bool = False, by_abs_val: bool = True) -> np.ndarray: """ Shift the center of mass of an array to the given position by cyclic permutation :param arr: 2d array, works best for well-centered feature with limited support :param y: position parameter :param x: position parameter for second dimension :param pos: tuple with the new position, overriding y,x values. should be used for higher-dimensional arrays :param move_maximum: if true, look only at max-value :param by_abs_val: take abs value for the determination of max-val or center-of-mass :return: array like original """ if move_maximum: if by_abs_val or arr.dtype in [np.complex64, np.complex128]: old = np.floor(measurements.maximum_position(abs(arr))) else: old = np.floor(measurements.maximum_position(arr)) else: if by_abs_val or arr.dtype in [np.complex64, np.complex128]: old = np.floor(measurements.center_of_mass(abs(arr))) else: old = np.floor(measurements.center_of_mass(arr)) if pos is not None: # dimension-independent method shifts = tuple([int(np.round(pos[i]-old[i])) for i in range(len(pos))]) dims = tuple([i for i in range(len(pos))]) temp = np.roll(arr, shift=shifts, axis=dims) else: # old method temp = shift_array(arr, int(y - old[0]), int(x - old[1])) return temp def shifted_fft(arr, axes=None): """ Combined fftshift and fft routine, based on scipy.fftpack Args: arr: numpy array axes: identical to argument for scipy.fftpack.fft Returns: transformed array """ return fft.ifftshift(fft.fftn(fft.fftshift(arr, axes=axes), axes=axes), axes=axes) def shifted_ifft(arr, axes=None): """ Combined fftshift and fft routine, based on scipy.fftpack Args: arr: numpy array axes: identical to argument for scipy.fftpack.fft Returns: transformed array """ return fft.fftshift(fft.ifftn(fft.ifftshift(arr, axes=axes), axes=axes), axes=axes)