from scipy import import Gnuplot from scipy import fftpack import Gnup

  • Anonymous
  • Python
  • 24 Jan 2009 
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from scipy import *

import Gnuplot

from scipy import fftpack

import Gnuplot

import math

import copy



y = [[], [], [], []]

power = copy.deepcopy(y)

period = copy.deepcopy(y)

p_data = [ [[],[]] , [[],[]] , [[],[]] , [[],[]] ]

nyquist=1./2



for i in xrange(32):

    y[0].append(math.sin(i)/100.)

for i in xrange(1,4):

    y[i] = copy.deepcopy(y[0])



# randomised y

for i in xrange(32):

    y[1][i] += random.random()



# random inserts and doubled range

for i in xrange(1, 63, 2):

    if ( random.random() >= 0.75 ) and ( i < len(y[2]) ):

        y[2].insert(i-1, y[2][i-1])

    y[3].insert(i-1, y[3][i-1])



for i in xrange(0, 4):

    Y = fft(y[i])

    ni = len(Y)/2

    nf = len(Y)/2.0

    freq = array(range(ni))/(nf)*nyquist



    power[i] = abs( Y[1:ni] )**2

    period[i] = 1./freq

    data1 = zip(range(len(y[i])-1), y[i])

    data2 = zip(period[i][1:len(period[i])], power[i])

    p_data[i][0] = Gnuplot.PlotItems.Data(data1, with="lines", title="signal" )

    p_data[i][1] = Gnuplot.PlotItems.Data(data2, with="lines", title="fft power" )



plt = Gnuplot.Gnuplot()

plt.plot(p_data[0][0], p_data[0][1], p_data[1][0], p_data[1][1], p_data[2][0], p_data[2][1], p_data[3][0], p_data[3][1])



#plt.xaxis((0,64))

#plt.ytitle('|FFT|**2')

#plt.grid("off")

#plt.output('sunspot_period.png','png medium transparent picsize 600 400')
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