pysteps.utils.spectral.rapsd¶

pysteps.utils.spectral.rapsd(Z, fft_method=None, return_freq=False, d=1.0, normalize=False, **fft_kwargs)¶

Compute radially averaged power spectral density (RAPSD) from the given 2D input field.

Parameters

Z: array_like: A 2d array of shape (M,N) containing the input field.
fft_method: object: A module or object implementing the same methods as numpy.fft and scipy.fftpack. If set to None, Z is assumed to represent the shifted discrete Fourier transform of the input field, where the origin is at the center of the array (see numpy.fft.fftshift or scipy.fftpack.fftshift).
return_freq: bool: Whether to also return the Fourier frequencies.
d: scalar: Sample spacing (inverse of the sampling rate). Defaults to 1. Applicable if return_freq is ‘True’.
normalize: bool: If True, normalize the power spectrum so that it sums to one.

Returns

out: ndarray: One-dimensional array containing the RAPSD. The length of the array is int(L/2)+1 (if L is even) or int(L/2) (if L is odd), where L=max(M,N).
freq: ndarray: One-dimensional array containing the Fourier frequencies.

References