mlab.psd and pyplot.psd are different!!!!
http://www.nabble.com/file/p24713274/psd_testpng.png http://www.nabble.com/file/p24713274/psd_testpng.png psd_testpng.png #This program below do reveal that mlab.psd and pyplot.psd are different import numpy as np import matplotlib.pyplot as plt import matplotlib.mlab as mlab dt = np.pi / 100. fs = 1. / dt t = np.arange(0, 8, dt) y = 10. * np.sin(2 * np.pi * 4 * t) + 5. * np.sin(2 * np.pi * 4.25 * t) y = y + np.random.randn(*t.shape) print "t=",t print "y=",y print "fs=",fs #Plot the raw time series fig = plt.figure() fig.subplots_adjust(hspace=0.6, wspace=0.5) # ax = fig.add_subplot(3, 1, 1) plt.title('Data') ax.plot(t,y) ax = fig.add_subplot(3, 1, 2) plt.title('psd using pyplot') ax.psd(y,Fs=fs,scale_by_freq=False) ax = fig.add_subplot(3, 1, 3) plt.title('psd using mlab') x,y=mlab.psd(y,Fs=fs,scale_by_freq=False) ax.plot(y,x) plt.show() Lewis, Ambrose J. wrote: > > Hi All: > > I'm trying to use the matplotlib psd function to plot some data. The > result from MATLAB's pWelch function looks vastly different. > > Any suggestions/recommendations would be greatly appreciated! > > THANXS > > amb > > > > Here is the MATLAB code: > > Fs = 13e6; > > fid = fopen('C:\asp\roseRT\ics_output.bin', 'r', 'ieee-le'); > > s = fread(fid, [2, Inf], 'int32'); > > fclose(fid); > > z = complex(s(2,:), s(1,:)); > > pwelch(z, [], [], [], Fs) > > > > And here is the (hypothetically) equivalent Python/matplotlib code: > > datatype = np.complex64 > > fd = open(self.filename, 'rb') > > read_data = np.fromfile(file=fd, dtype=datatype) > > Pxx,freqs = psd(read_data,Fs=13000000) > > self.axes.plot(freqs, 10*log10(Pxx) ) > > self.canvas.draw() > > > > Ambrose Lewis > > SAIC > > 4001 N Fairfax Drive, Suite 400 > > Arlington, VA 22203 > > 703.558.2786 > > ambrose.j.le...@saic.com > > > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by: > SourcForge Community > SourceForge wants to tell your story. > http://p.sf.net/sfu/sf-spreadtheword > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > -- View this message in context: http://www.nabble.com/psd-question...-tp21458898p24713274.html Sent from the matplotlib - users mailing list archive at Nabble.com. ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
