scipy.fftpack.rfftfreq¶
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scipy.fftpack.rfftfreq(n, d=1.0)[source]¶ DFT sample frequencies (for usage with rfft, irfft).
The returned float array contains the frequency bins in cycles/unit (with zero at the start) given a window length n and a sample spacing d:
f = [0,1,1,2,2,...,n/2-1,n/2-1,n/2]/(d*n) if n is even f = [0,1,1,2,2,...,n/2-1,n/2-1,n/2,n/2]/(d*n) if n is odd
- Parameters
- nint
Window length.
- dscalar, optional
Sample spacing. Default is 1.
- Returns
- outndarray
The array of length n, containing the sample frequencies.
Examples
>>> from scipy import fftpack >>> sig = np.array([-2, 8, 6, 4, 1, 0, 3, 5], dtype=float) >>> sig_fft = fftpack.rfft(sig) >>> n = sig_fft.size >>> timestep = 0.1 >>> freq = fftpack.rfftfreq(n, d=timestep) >>> freq array([ 0. , 1.25, 1.25, 2.5 , 2.5 , 3.75, 3.75, 5. ])