dask 2021.10.0

ParametersReturns
rfftfreq(n, d=1.0, chunks='auto')

This docstring was copied from numpy.fft.rfftfreq.

Some inconsistencies with the Dask version may exist.

The returned float array f contains the frequency bin centers in cycles per unit of the sample spacing (with zero at the start). For instance, if the sample spacing is in seconds, then the frequency unit is cycles/second.

Given a window length n and a sample spacing d:

f = [0, 1, ...,     n/2-1,     n/2] / (d*n)   if n is even
f = [0, 1, ..., (n-1)/2-1, (n-1)/2] / (d*n)   if n is odd

Unlike fftfreq (but like scipy.fftpack.rfftfreq ) the Nyquist frequency component is considered to be positive.

Parameters

n : int

Window length.

d : scalar, optional

Sample spacing (inverse of the sampling rate). Defaults to 1.

Returns

f : ndarray

Array of length n//2 + 1 containing the sample frequencies.

Return the Discrete Fourier Transform sample frequencies (for usage with rfft, irfft).

Examples

This example is valid syntax, but we were not able to check execution
>>> signal = np.array([-2, 8, 6, 4, 1, 0, 3, 5, -3, 4], dtype=float)  # doctest: +SKIP
... fourier = np.fft.rfft(signal) # doctest: +SKIP
... n = signal.size # doctest: +SKIP
... sample_rate = 100 # doctest: +SKIP
... freq = np.fft.fftfreq(n, d=1./sample_rate) # doctest: +SKIP
... freq # doctest: +SKIP array([ 0., 10., 20., ..., -30., -20., -10.])
This example is valid syntax, but we were not able to check execution
>>> freq = np.fft.rfftfreq(n, d=1./sample_rate)  # doctest: +SKIP
... freq # doctest: +SKIP array([ 0., 10., 20., 30., 40., 50.])
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File: /dask/array/fft.py#251
type: <class 'function'>
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