Revision: 7121
http://matplotlib.svn.sourceforge.net/matplotlib/?rev=7121&view=rev
Author: ryanmay
Date: 2009-05-18 20:50:20 +0000 (Mon, 18 May 2009)
Log Message:
-----------
Move code for wrapping negative frequencies from specgram() into
_spectral_helper(), so that psd(), csd(), and cohere() can benefit from this
functionality as well. While this changes API a little, this is much more
sensible behavior.
Modified Paths:
--------------
trunk/matplotlib/CHANGELOG
trunk/matplotlib/doc/api/api_changes.rst
trunk/matplotlib/lib/matplotlib/mlab.py
Added Paths:
-----------
trunk/matplotlib/examples/pylab_examples/psd_demo_complex.py
Modified: trunk/matplotlib/CHANGELOG
===================================================================
--- trunk/matplotlib/CHANGELOG 2009-05-18 19:19:33 UTC (rev 7120)
+++ trunk/matplotlib/CHANGELOG 2009-05-18 20:50:20 UTC (rev 7121)
@@ -1,4 +1,7 @@
-2009-05-18 Fix the linespacing bug of multiline text (#1239682). See
+2009-05-18 Make psd(), csd(), and cohere() wrap properly for complex/two-sided
+ versions, like specgram() (SF #2791686) - RMM
+
+2009-05-18 Fix the linespacing bug of multiline text (#1239682). See
examples/pylab_examples/multiline.py -JJL
2009-05-18 Add *annotation_clip* attr. for text.Annotation class.
Modified: trunk/matplotlib/doc/api/api_changes.rst
===================================================================
--- trunk/matplotlib/doc/api/api_changes.rst 2009-05-18 19:19:33 UTC (rev
7120)
+++ trunk/matplotlib/doc/api/api_changes.rst 2009-05-18 20:50:20 UTC (rev
7121)
@@ -19,6 +19,12 @@
Changes for 0.98.x
==================
+* psd(), csd(), and cohere() will now automatically wrap negative
+ frequency components to the beginning of the returned arrays.
+ This is much more sensible behavior and makes them consistent
+ with specgram(). The previous behavior was more of an oversight
+ than a design decision.
+
* Added new keyword parameters *nonposx*, *nonposy* to
:class:`matplotlib.axes.Axes` methods that set log scale
parameters. The default is still to mask out non-positive
Added: trunk/matplotlib/examples/pylab_examples/psd_demo_complex.py
===================================================================
--- trunk/matplotlib/examples/pylab_examples/psd_demo_complex.py
(rev 0)
+++ trunk/matplotlib/examples/pylab_examples/psd_demo_complex.py
2009-05-18 20:50:20 UTC (rev 7121)
@@ -0,0 +1,38 @@
+#This is a ported version of a Matlab example from the signal processing
+#toolbox that showed some difference at one time between Matplotlib's and
+#MatLab's scaling of the PSD. This differs from psd_demo3.py in that
+#this uses a complex signal, so we can see that complex PSD's work properly
+import numpy as np
+import matplotlib.pyplot as plt
+import matplotlib.mlab as mlab
+
+fs = 1000
+t = np.linspace(0, 0.3, 301)
+A = np.array([2, 8]).reshape(-1, 1)
+f = np.array([150, 140]).reshape(-1, 1)
+xn = (A * np.exp(2j * np.pi * f * t)).sum(axis=0) + 5 *
np.random.randn(*t.shape)
+
+yticks = np.arange(-50, 30, 10)
+xticks = np.arange(-500,550,100)
+plt.subplots_adjust(hspace=0.45, wspace=0.3)
+ax = plt.subplot(1, 2, 1)
+
+plt.psd(xn, NFFT=301, Fs=fs, window=mlab.window_none, pad_to=1024,
+ scale_by_freq=True)
+plt.title('Periodogram')
+plt.yticks(yticks)
+plt.xticks(xticks)
+plt.grid(True)
+plt.xlim(-500, 500)
+
+plt.subplot(1, 2, 2, sharex=ax, sharey=ax)
+plt.psd(xn, NFFT=150, Fs=fs, window=mlab.window_none, noverlap=75, pad_to=512,
+ scale_by_freq=True)
+plt.title('Welch')
+plt.xticks(xticks)
+plt.yticks(yticks)
+plt.ylabel('')
+plt.grid(True)
+plt.xlim(-500, 500)
+
+plt.show()
Modified: trunk/matplotlib/lib/matplotlib/mlab.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/mlab.py 2009-05-18 19:19:33 UTC (rev
7120)
+++ trunk/matplotlib/lib/matplotlib/mlab.py 2009-05-18 20:50:20 UTC (rev
7121)
@@ -327,6 +327,11 @@
t = 1./Fs * (ind + NFFT / 2.)
freqs = float(Fs) / pad_to * np.arange(numFreqs)
+ if (np.iscomplexobj(x) and sides == 'default') or sides == 'twosided':
+ # center the frequency range at zero
+ freqs = np.concatenate((freqs[numFreqs//2:] - Fs, freqs[:numFreqs//2]))
+ Pxy = np.concatenate((Pxy[numFreqs//2:, :], Pxy[:numFreqs//2, :]), 0)
+
return Pxy, freqs, t
#Split out these keyword docs so that they can be used elsewhere
@@ -485,11 +490,6 @@
noverlap, pad_to, sides, scale_by_freq)
Pxx = Pxx.real #Needed since helper implements generically
- if (np.iscomplexobj(x) and sides == 'default') or sides == 'twosided':
- # center the frequency range at zero
- freqs = np.concatenate((freqs[NFFT/2:]-Fs,freqs[:NFFT/2]))
- Pxx = np.concatenate((Pxx[NFFT/2:,:],Pxx[:NFFT/2,:]),0)
-
return Pxx, freqs, t
specgram.__doc__ = specgram.__doc__ % kwdocd
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