CODEWITHSUNDEEP
pythonmatplotlib
questionhang
questionhang

Reputation: 763

how to remove the unecessay straight line in the plot?

The data in the array freq below is not sorted.

Is there any convenient way to remove the the unecessay straight line from left to right in my plot?

import pylab as pl
import numpy as np
timepoints=np.loadtxt("timesequence",usecols=(1,),unpack=True,delimiter=",")
t=np.histogram(timepoints,bins=500)[0]
sp = np.fft.fft(t)
freq = np.fft.fftfreq(t.shape[-1],d=0.0005)
print freq
pl.plot(freq*2*np.pi, np.sqrt(sp.real**2+sp.imag**2))
pl.show()

enter image description here

Upvotes: 3

Views: 855

Answers (1)

benten
benten

Reputation: 1991

As you have it, the plot starts at the peak zero point, then works its way to the right, then jumps to the far left and works its way back to the middle. It is NOT a simple left-to-right kind of time-series (in case that's what you think it is).

One workaround is to plot the positive points in 'freq' separately from the negative points in 'freq'. Replace your pl.plot line of code with the following:

mask = freq>=0
pl.plot(freq[mask]*2*np.pi, np.sqrt(sp[mask].real**2+sp[mask].imag**2))
pl.plot(freq[~mask]*2*np.pi, np.sqrt(sp[~mask].real**2+sp[~mask].imag**2))

ps, You'll need to set the colors so they match.

Upvotes: 1

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