mars.tensor.fft.rfftfreq¶
- mars.tensor.fft.rfftfreq(n, d=1.0, gpu=False, chunk_size=None)[源代码]¶
Return the Discrete Fourier Transform sample frequencies (for usage with rfft, irfft).
The returned float tensor 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.
- 参数
- 返回
f – Tensor of length
n//2 + 1
containing the sample frequencies.- 返回类型
Tensor
实际案例
>>> import mars.tensor as mt
>>> signal = mt.array([-2, 8, 6, 4, 1, 0, 3, 5, -3, 4], dtype=float) >>> fourier = mt.fft.rfft(signal) >>> n = signal.size >>> sample_rate = 100 >>> freq = mt.fft.fftfreq(n, d=1./sample_rate) >>> freq.execute() array([ 0., 10., 20., 30., 40., -50., -40., -30., -20., -10.]) >>> freq = mt.fft.rfftfreq(n, d=1./sample_rate) >>> freq.execute() array([ 0., 10., 20., 30., 40., 50.])