[Matplotlib-users] specgram bug
Hi, not 100% sure this is a bug, but here goes: In file matplotlib/lib/matplotlib/mlab.py, the functions psd (power spectral density) and specgram returns the real part of the fourier transform. % grep -n Pxx.real mlab.py 390:return Pxx.real,freqs 470:Pxx = Pxx.real #Needed since helper implements generically (git version 4f902fac1c5bf267e3fdeb4c2045926d7498e85a, cloned from github today) This all means that the specgram plot routine yields the real part of the Fourier transform, rather than its absolute square (forgetting normalization for simplicity of discussion). The definition of the PSD is that it is the absolute square of the Fourier transform: https://en.wikipedia.org/wiki/Power_spectral_density#Energy_spectral_density Hence, I believe this is a bug which should be fixed. Cheers Paul -- Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram bug
Hi, If you trace back into the code further, you will see that the Pxx is computed as X = fft(x), Pxx = X * conj(X) which is real, but the data type will be complex with a ~0 imaginary part (up to floating point precision). Thus the Pxx.real is just to ensure that the resulting data type is real instead of complex to save memory. Glenn On Mon, Nov 12, 2012 at 11:42 AM, Paul Anton Letnes paul.anton.let...@gmail.com wrote: Hi, not 100% sure this is a bug, but here goes: In file matplotlib/lib/matplotlib/mlab.py, the functions psd (power spectral density) and specgram returns the real part of the fourier transform. % grep -n Pxx.real mlab.py 390:return Pxx.real,freqs 470:Pxx = Pxx.real #Needed since helper implements generically (git version 4f902fac1c5bf267e3fdeb4c2045926d7498e85a, cloned from github today) This all means that the specgram plot routine yields the real part of the Fourier transform, rather than its absolute square (forgetting normalization for simplicity of discussion). The definition of the PSD is that it is the absolute square of the Fourier transform: https://en.wikipedia.org/wiki/Power_spectral_density#Energy_spectral_density Hence, I believe this is a bug which should be fixed. Cheers Paul -- Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram bug
If you're using pyplot.specgram (i.e. from pylab import *; specgram(...)), note that the plot is in dB, hence the negative values. I'm surprised this fact isn't mentioned in the documentation: http://matplotlib.org/api/pyplot_api.html?highlight=specgram#matplotlib.pyplot.specgram However, when in doubt, look at the code. On Mon, Nov 12, 2012 at 12:28 PM, Paul Anton Letnes paul.anton.let...@gmail.com wrote: Heh, that's funny. Now then, why do my plots come out with negative values all over the place? That's why I started digging around. After all, X * conj(X) should be equal to the absolute square of X, right? Paul On 12. nov. 2012, at 21:00, G Jones wrote: Hi, If you trace back into the code further, you will see that the Pxx is computed as X = fft(x), Pxx = X * conj(X) which is real, but the data type will be complex with a ~0 imaginary part (up to floating point precision). Thus the Pxx.real is just to ensure that the resulting data type is real instead of complex to save memory. Glenn On Mon, Nov 12, 2012 at 11:42 AM, Paul Anton Letnes paul.anton.let...@gmail.com wrote: Hi, not 100% sure this is a bug, but here goes: In file matplotlib/lib/matplotlib/mlab.py, the functions psd (power spectral density) and specgram returns the real part of the fourier transform. % grep -n Pxx.real mlab.py 390:return Pxx.real,freqs 470:Pxx = Pxx.real #Needed since helper implements generically (git version 4f902fac1c5bf267e3fdeb4c2045926d7498e85a, cloned from github today) This all means that the specgram plot routine yields the real part of the Fourier transform, rather than its absolute square (forgetting normalization for simplicity of discussion). The definition of the PSD is that it is the absolute square of the Fourier transform: https://en.wikipedia.org/wiki/Power_spectral_density#Energy_spectral_density Hence, I believe this is a bug which should be fixed. Cheers Paul -- Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram memory problem
On Sat, Feb 4, 2012 at 9:44 AM, Fabrice Silva si...@lma.cnrs-mrs.fr wrote: Le vendredi 03 février 2012 à 17:39 +, David Craig a écrit : sure how to get it to plot the outputs from specgram. I use specgram as follows, Pxx, freqs, bins, im = plt.specgram(..) what am I trying imshow?? plt.specgram computes the spectrogram and when calls imshow to display the resulting array into an image Please tell the shape of Pxx, and try the following import numpy as np import matplotlib.pyplot as plt a = np.empty((12000, 14400), dtype=float) plt.imshow(a) plt.show() Le samedi 04 février 2012 à 10:30 +, David Craig a écrit : Pxx has shape (6001, 1430) and when I tried the lines of code it returned the following memory error, Traceback (most recent call last): File /usr/lib/python2.7/site-packages/matplotlib/backends/backend_gtk.py, line 394, in expose_event self._render_figure(self._pixmap, w, h) File /usr/lib/python2.7/site-packages/matplotlib/backends/backend_gtkagg.py, line 75, in _render_figure FigureCanvasAgg.draw(self) File /usr/lib/python2.7/site-packages/matplotlib/backends/backend_agg.py, line 394, in draw self.figure.draw(self.renderer) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/figure.py, line 798, in draw func(*args) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/axes.py, line 1946, in draw a.draw(renderer) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 354, in draw im = self.make_image(renderer.get_image_magnification()) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 569, in make_image transformed_viewLim) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 201, in _get_unsampled_image x = self.to_rgba(self._A, self._alpha) File /usr/lib/python2.7/site-packages/matplotlib/cm.py, line 193, in to_rgba x = self.norm(x) File /usr/lib/python2.7/site-packages/matplotlib/colors.py, line 802, in __call__ val = ma.asarray(value).astype(np.float) File /usr/lib/python2.7/site-packages/numpy/ma/core.py, line 2908, in astype output = self._data.astype(newtype).view(type(self)) MemoryError Please, answer on the mailing list, It confirms that the troubles lie in the rendering of images. Could you tell the versions of numpy and matplotlib you are using, and the characteristics of the computer you are working on ? -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram memory problem
I'm using a lenovo laptop with fedora 16. It has 2.9 GiB memory and 4 intel core CPUs @ 2.3GHz each. Available disk space is 147.9GiB. numpy 1.6.0 matplotlib 1.0.1 On 6 Feb 2012, at 10:29, Fabrice Silva wrote: On Sat, Feb 4, 2012 at 9:44 AM, Fabrice Silva si...@lma.cnrs- mrs.fr wrote: Le vendredi 03 février 2012 à 17:39 +, David Craig a écrit : sure how to get it to plot the outputs from specgram. I use specgram as follows, Pxx, freqs, bins, im = plt.specgram(..) what am I trying imshow?? plt.specgram computes the spectrogram and when calls imshow to display the resulting array into an image Please tell the shape of Pxx, and try the following import numpy as np import matplotlib.pyplot as plt a = np.empty((12000, 14400), dtype=float) plt.imshow(a) plt.show() Le samedi 04 février 2012 à 10:30 +, David Craig a écrit : Pxx has shape (6001, 1430) and when I tried the lines of code it returned the following memory error, Traceback (most recent call last): File /usr/lib/python2.7/site-packages/matplotlib/backends/ backend_gtk.py, line 394, in expose_event self._render_figure(self._pixmap, w, h) File /usr/lib/python2.7/site-packages/matplotlib/backends/ backend_gtkagg.py, line 75, in _render_figure FigureCanvasAgg.draw(self) File /usr/lib/python2.7/site-packages/matplotlib/backends/ backend_agg.py, line 394, in draw self.figure.draw(self.renderer) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/figure.py, line 798, in draw func(*args) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/axes.py, line 1946, in draw a.draw(renderer) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 354, in draw im = self.make_image(renderer.get_image_magnification()) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 569, in make_image transformed_viewLim) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 201, in _get_unsampled_image x = self.to_rgba(self._A, self._alpha) File /usr/lib/python2.7/site-packages/matplotlib/cm.py, line 193, in to_rgba x = self.norm(x) File /usr/lib/python2.7/site-packages/matplotlib/colors.py, line 802, in __call__ val = ma.asarray(value).astype(np.float) File /usr/lib/python2.7/site-packages/numpy/ma/core.py, line 2908, in astype output = self._data.astype(newtype).view(type(self)) MemoryError Please, answer on the mailing list, It confirms that the troubles lie in the rendering of images. Could you tell the versions of numpy and matplotlib you are using, and the characteristics of the computer you are working on ? -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram memory problem
On Mon, Feb 6, 2012 at 11:59 AM, David Craig dcdavem...@gmail.com wrote: I'm using a lenovo laptop with fedora 16. It has 2.9 GiB memory and 4 intel core CPUs @ 2.3GHz each. Available disk space is 147.9GiB. numpy 1.6.0 matplotlib 1.0.1 32-bit or 64-bit OS? Please use 'uname -a' to tell us, because you can install a 32-bit OS on a 64-bit machine. Ben Root -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram memory problem
uname -a gives, Linux David 3.2.2-1.fc16.i686 #1 SMP Thu Jan 26 03:38:31 UTC 2012 i686 i686 i386 GNU/Linux On Mon, Feb 6, 2012 at 6:07 PM, Benjamin Root ben.r...@ou.edu wrote: On Mon, Feb 6, 2012 at 11:59 AM, David Craig dcdavem...@gmail.com wrote: I'm using a lenovo laptop with fedora 16. It has 2.9 GiB memory and 4 intel core CPUs @ 2.3GHz each. Available disk space is 147.9GiB. numpy 1.6.0 matplotlib 1.0.1 32-bit or 64-bit OS? Please use 'uname -a' to tell us, because you can install a 32-bit OS on a 64-bit machine. Ben Root -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram memory problem
Le vendredi 03 février 2012 à 17:39 +, David Craig a écrit : sure how to get it to plot the outputs from specgram. I use specgram as follows, Pxx, freqs, bins, im = plt.specgram(..) what am I trying imshow?? plt.specgram computes the spectrogram and when calls imshow to display the resulting array into an image Please tell the shape of Pxx, and try the following import numpy as np import matplotlib.pyplot as plt a = np.empty((12000, 14400), dtype=float) plt.imshow(a) plt.show() -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] specgram memory problem
Hi, I am using matplotlib to produce some spectrograms for seismic data. I am looking at a 10 day period with a sample rate of 20sps. I would like to have my spectrogram to be composed of 10 minute windows with an overlap of 90%. However when I try and run my script I run out of memory. I can produce the spectrogram for a maximum of 3 days before an error occurs. I have also tried to produce a spectrogram for each day and stick them together using subplot, but I then get the error given below. Anyone know a way around this?? Thanks, David Traceback (most recent call last): File /usr/lib/python2.7/site-packages/matplotlib/backends/backend_gtk.py, line 394, in expose_event self._render_figure(self._pixmap, w, h) File /usr/lib/python2.7/site-packages/matplotlib/backends/backend_gtkagg.py, line 75, in _render_figure FigureCanvasAgg.draw(self) File /usr/lib/python2.7/site-packages/matplotlib/backends/backend_agg.py, line 394, in draw self.figure.draw(self.renderer) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/figure.py, line 798, in draw func(*args) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/axes.py, line 1946, in draw a.draw(renderer) File /usr/lib/python2.7/site-packages/matplotlib/artist.py, line 55, in draw_wrapper draw(artist, renderer, *args, **kwargs) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 354, in draw im = self.make_image(renderer.get_image_magnification()) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 569, in make_image transformed_viewLim) File /usr/lib/python2.7/site-packages/matplotlib/image.py, line 201, in _get_unsampled_image x = self.to_rgba(self._A, self._alpha) File /usr/lib/python2.7/site-packages/matplotlib/cm.py, line 194, in to_rgba x = self.cmap(x, alpha=alpha, bytes=bytes) File /usr/lib/python2.7/site-packages/matplotlib/colors.py, line 551, in __call__ rgba = np.empty(shape=xa.shape+(4,), dtype=lut.dtype) MemoryError -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram memory problem
Le vendredi 03 février 2012 à 12:11 +, David Craig a écrit : Hi, I am using matplotlib to produce some spectrograms for seismic data. I am looking at a 10 day period with a sample rate of 20sps. I would like to have my spectrogram to be composed of 10 minute windows with an overlap of 90%. However when I try and run my script I run out of memory. I can produce the spectrogram for a maximum of 3 days before an error occurs. I have also tried to produce a spectrogram for each day and stick them together using subplot, but I then get the error given below. Anyone know a way around this?? Thanks, David It seems that the MemoryError does not occur when computing the spectrogram, but when rendering it. A quick rule of a thumb tells me that you have to display an image that is 12000x14400: 12000 frequencies, as you are using windows with 12000 samples (no padded assumed) 14400 windows, due to the 90% overlap Having a 4-channel for the RGBA image may throw the MemoryError. Can you check by trying to imshow such an array ? You can also reduce the overlap, the one you used lead to a spectrum computation each minute... -- Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] specgram
Hi, I am trying to produce a spectrogram for my data set and am having an issue with the color map. My data is filtered between 0.02 and 1.0Hz, but specgram() produces an image in the range 0 to 10Hz. Also the color map is not set properly. I would like to have it so the colormap ranges from the min and max powers obtained by specgram. Anyone know how to do this? My code is below. Pxx, freqs, bins, im = plt.specgram(data, NFFT=nfft, Fs=sps, detrend=py.detrend_none, window=py.window_hanning, noverlap=nfft/2, cmap=None, xextent=None, pad_to=None, sides='default', scale_by_freq=None) plt.ylim(0,1) plt.colorbar() plt.show() thanks, D -- Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
[Matplotlib-users] specgram with zeros array
I am using Matplotlib version 1.0.1 and I get errors if I try the following:
import matplotlib.pyplot as plt
import numpy as np
plt.specgram(np.zeros(50))
I have pasted the error output below, but hopefully it would reproduce
in other systems. I'm not sure if this is intended behavior and was
wondering. I came across this when I was plotting the specgram of my
sound input, but my microphone was muted!
---
AttributeErrorTraceback (most recent call last)
/usr/local/lib/python2.6/dist-packages/matplotlib/backends/backend_wx.pyc in
_onPaint(self, evt)
1192 drawDC = wx.PaintDC(self)
1193 if not self._isDrawn:
- 1194 self.draw(drawDC=drawDC)
1195 else:
1196 self.gui_repaint(drawDC=drawDC)
/usr/local/lib/python2.6/dist-packages/matplotlib/backends/backend_wxagg.pyc
in draw(self, drawDC)
57
58 DEBUG_MSG(draw(), 1, self)
--- 59 FigureCanvasAgg.draw(self)
60
61 self.bitmap =
_convert_agg_to_wx_bitmap(self.get_renderer(), None)
/usr/local/lib/python2.6/dist-packages/matplotlib/backends/backend_agg.pyc
in draw(self)
392
393 self.renderer = self.get_renderer()
-- 394 self.figure.draw(self.renderer)
395
396 def get_renderer(self):
/usr/local/lib/python2.6/dist-packages/matplotlib/artist.pyc in
draw_wrapper(artist, renderer, *args, **kwargs)
53 def draw_wrapper(artist, renderer, *args, **kwargs):
54 before(artist, renderer)
--- 55 draw(artist, renderer, *args, **kwargs)
56 after(artist, renderer)
57
/usr/local/lib/python2.6/dist-packages/matplotlib/figure.pyc in
draw(self, renderer)
796 dsu.sort(key=itemgetter(0))
797 for zorder, func, args in dsu:
-- 798 func(*args)
799
800 renderer.close_group('figure')
/usr/local/lib/python2.6/dist-packages/matplotlib/artist.pyc in
draw_wrapper(artist, renderer, *args, **kwargs)
53 def draw_wrapper(artist, renderer, *args, **kwargs):
54 before(artist, renderer)
--- 55 draw(artist, renderer, *args, **kwargs)
56 after(artist, renderer)
57
/usr/local/lib/python2.6/dist-packages/matplotlib/axes.pyc in draw(self,
renderer, inframe)
1944
1945 for zorder, a in dsu:
- 1946 a.draw(renderer)
1947
1948 renderer.close_group('axes')
/usr/local/lib/python2.6/dist-packages/matplotlib/artist.pyc in
draw_wrapper(artist, renderer, *args, **kwargs)
53 def draw_wrapper(artist, renderer, *args, **kwargs):
54 before(artist, renderer)
--- 55 draw(artist, renderer, *args, **kwargs)
56 after(artist, renderer)
57
/usr/local/lib/python2.6/dist-packages/matplotlib/image.pyc in
draw(self, renderer, *args, **kwargs)
352 warnings.warn(Image will not be shown
correctly with this backend.)
353
-- 354 im = self.make_image(renderer.get_image_magnification())
355 if im is None:
356 return
/usr/local/lib/python2.6/dist-packages/matplotlib/image.pyc in
make_image(self, magnification)
567 im, xmin, ymin, dxintv, dyintv, sx, sy = \
568 self._get_unsampled_image(self._A, [_x1, _x2, _y1,
_y2],
-- 569 transformed_viewLim)
570
571 fc = self.axes.patch.get_facecolor()
/usr/local/lib/python2.6/dist-packages/matplotlib/image.pyc in
_get_unsampled_image(self, A, image_extents, viewlim)
199 else:
200 if self._rgbacache is None:
-- 201 x = self.to_rgba(self._A, self._alpha)
202 self._rgbacache = x
203 else:
/usr/local/lib/python2.6/dist-packages/matplotlib/cm.pyc in
to_rgba(self, x, alpha, bytes)
191 pass
192 x = ma.asarray(x)
-- 193 x = self.norm(x)
194 x = self.cmap(x, alpha=alpha, bytes=bytes)
195 return x
/usr/local/lib/python2.6/dist-packages/matplotlib/colors.pyc in
__call__(self, value, clip)
809 if vmin vmax:
810 raise ValueError(minvalue must be less than or
equal to maxvalue)
-- 811 elif vmin==vmax:
812 result = 0.0 * val
813 else:
/usr/lib/python2.6/dist-packages/numpy/ma/core.pyc in __eq__(self, other)
3117 mask = np.all([[f[n].all() for n in
mask.dtype.names]
3118 for f in mask], axis=axis)
- 3119 check._mask = mask
3120 return check
3121 #
AttributeError: 'numpy.bool_' object has no attribute '_mask'
[Matplotlib-users] specgram: Warning: divide by zero encountered in log10
Hi guys, I'm trying to make a specgram() for some wave samples that I have read into 'data' using pyaudiolab's read_frames() (put into wavread()) When I do from wavread import * from pylab import * from statistics import * data, datasize, samplerate, channels = wavread(myfile.wav) specgram(data) I get: Warning: divide by zero encountered in log10 (array([[ 2.26730611e-02, 1.51890672e-02, 7.78123371e-03, ..., 0.e+00, 0.e+00, 0.e+00], [ 9.11969843e-03, 2.81931459e-03, 3.13995580e-03, ..., 0.e+00, 0.e+00, 0.e+00], [ 7.25346631e-04, 4.83291216e-05, 2.59076878e-04, ..., 0.e+00, 0.e+00, 0.e+00], ..., [ 5.19279887e-08, 1.53242938e-07, 1.46461798e-07, ..., 0.e+00, 0.e+00, 0.e+00], [ 1.00769359e-07, 2.00314891e-07, 3.04618029e-07, ..., 0.e+00, 0.e+00, 0.e+00], [ 2.86252093e-08, 5.42052713e-07, 1.50494595e-07, ..., 0.e+00, 0.e+00, 0.e+00]]), array([ 0. , 0.0078125, 0.015625 , 0.0234375, 0.03125 , 0.0390625, 0.046875 , 0.0546875, 0.0625 , 0.0703125, 0.078125 , 0.0859375, 0.09375 , 0.1015625, 0.109375 , 0.1171875, 0.125, 0.1328125, 0.140625 , 0.1484375, 0.15625 , 0.1640625, 0.171875 , 0.1796875, 0.1875 , 0.1953125, 0.203125 , 0.2109375, 0.21875 , 0.2265625, 0.234375 , 0.2421875, 0.25 , 0.2578125, 0.265625 , 0.2734375, 0.28125 , 0.2890625, 0.296875 , 0.3046875, 0.3125 , 0.3203125, 0.328125 , 0.3359375, 0.34375 , 0.3515625, 0.359375 , 0.3671875, 0.375, 0.3828125, 0.390625 , 0.3984375, 0.40625 , 0.4140625, 0.421875 , 0.4296875, 0.4375 , 0.4453125, 0.453125 , 0.4609375, 0.46875 , 0.4765625, 0.484375 , 0.4921875, 0.5 , 0.5078125, 0.515625 , 0.5234375, 0.53125 , 0.5390625, 0.546875 , 0.5546875, 0.5625 , 0.5703125, 0.578125 , 0.5859375, 0.59375 , 0.6015625, 0.609375 , 0.6171875, 0.625, 0.6328125, 0.640625 , 0.6484375, 0.65625 , 0.6640625, 0.671875 , 0.6796875, 0.6875 , 0.6953125, 0.703125 , 0.7109375, 0.71875 , 0.7265625, 0.734375 , 0.7421875, 0.75 , 0.7578125, 0.765625 , 0.7734375, 0.78125 , 0.7890625, 0.796875 , 0.8046875, 0.8125 , 0.8203125, 0.828125 , 0.8359375, 0.84375 , 0.8515625, 0.859375 , 0.8671875, 0.875, 0.8828125, 0.890625 , 0.8984375, 0.90625 , 0.9140625, 0.921875 , 0.9296875, 0.9375 , 0.9453125, 0.953125 , 0.9609375, 0.96875 , 0.9765625, 0.984375 , 0.9921875, 1. ]), array ([ 6.4000e+01, 1.2800e+02, 1.9200e+02, ..., 9.7344e+04, 9.7408e+04, 9.7472e+04]), matplotlib.image.AxesImage instance at 0x3324fa8) For another sample, I get a nice spectrogram. What can it be about my sample that would give me such an error? What is the error caused by? A Google on the error message provided me with nothing. Sincerely yours Niklas Saers- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] specgram: Warning: divide by zero encountered in log10
On 3/28/07, Niklas Saers [EMAIL PROTECTED] wrote: Hi guys, I'm trying to make a specgram() for some wave samples that I have read into 'data' using pyaudiolab's read_frames() (put into wavread()) When I do from wavread import * from pylab import * from statistics import * data, datasize, samplerate, channels = wavread(myfile.wav) specgram(data) I get: Warning: divide by zero encountered in log10 (array([[ 2.26730611e-02, 1.51890672e-02, 7.78123371e-03, ..., 0.e+00, 0.e+00, 0.e+00], [ 9.11969843e-03, 2.81931459e-03, 3.13995580e-03, ..., So there is no traceback, just a warning? Perhaps you could pickle or otherwise store data and write a simple test script which doesn't depend on any external packages (eg waveread) and post a link to the files and we'll take a look. My guess is that there is some frequency that has no power and the call to Z = 10*log10(Pxx) is failing because Pxx is zero for that frequency. We've seen this before, and if anyone has a suggestion on how this case *should* be handled, I'd be happy to hear some suggestions. JDH JDH - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV ___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
