matplotlib-users Mailing List for matplotlib

Hi Nicolas

Thanks for the post.  I'm going to finish optimizing all of the 
non-rendering pieces of my code, then I'll see if trying the hardware 
rendering makes sense.  Right now I am software rendering 3.5 million 
triangles in about 5 seconds, but the setup (masking etc) is taking 
about 40.  When I get the setup lower (which I think I will), I'll get 
back to you about this.

Thanks again
Howard

On 1/29/12 7:43 AM, Nicolas Rougier wrote:
>
>
> Thanks for posting the link to glumpy.
>
> As Benjamin explained, glumpy servers as a testbed for various 
> technics that could be implemented later in matplotlib. The main 
> problem today is that if you want to benefit from hardware 
> acceleration, you have to use some GL features that are not compatible 
> with he whole matplotlib framework (and we need to ensure some degree 
> of compatibilty). I do not have yet a clean solution and I'm still 
> experimenting.
>
> For your tricontourf problem, I think it might be solved quite easily 
> with the proper GL shader  but I would need a complete (and basic) 
> matplotlib script example to check if this is actually the case.
>
>
> Nicolas
>
>
> On Jan 27, 2012, at 23:12 , Benjamin Root wrote:
>
>> On Fri, Jan 27, 2012 at 10:06 AM, Howard <ho...@re... 
>> <mailto:ho...@re...>> wrote:
>>
>>     On 1/27/12 3:39 AM, Ian Thomas wrote:
>>>     On 26 January 2012 19:36, Howard <ho...@re...
>>>     <mailto:ho...@re...>> wrote:
>>>
>>>         I'm rendering some images with about 3.5 million triangles
>>>         into a 512x512 png file using tricontourf. I'm running this
>>>         in a virtual machine, and I'm pretty sure that there is no
>>>         graphics rendering hardware being used. Is it possible,
>>>         assuming the hardware was available, to make tricontourf use
>>>         the rendering hardware?  Will that happen by default?
>>>
>>>
>>>     You are correct, there is no graphics hardware rendering. 
>>>     Rendering is controlled by the various matplotlib backends, and
>>>     to my knowledge there are  no backends currently available that
>>>     use hardware rendering.
>>>
>>>     There has been some work done on an OpenGL backend, but I am not
>>>     sure of the status of this.  The last time I checked it was
>>>     pretty experimental.  Perhaps someone involved with it can
>>>     comment on its current status.
>>>
>>>     Ian Thomas
>>     Ian
>>
>>     Thanks very much for the reply. If it helps whoever is doing the
>>     OpenGL backend, I may be able to play with it a bit.
>>
>>
>>     Howard
>>
>>
>> That would be the Glumpy project.
>>
>> http://code.google.com/p/glumpy/
>>
>> As stated in an email response a while back, glumpy is intended to be 
>> a testbed for developing the OpenGL backend for future inclusion into 
>> matplotlib.
>>
>> Cheers!
>> Ben Root
>>
>> ------------------------------------------------------------------------------
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-- 
Howard Lander <mailto:ho...@re...>
Senior Research Software Developer
Renaissance Computing Institute (RENCI) <http://www.renci.org>
The University of North Carolina at Chapel Hill
Duke University
North Carolina State University
100 Europa Drive
Suite 540
Chapel Hill, NC 27517
919-445-9651

nahren manuel wrote:
> 
> Hello ,
> I have a two dimensional array, 40X20(rowsXcolumns). Each of the 40 rows
> themselves hold values of the bins of a distribution (which is not always
> normal, can expect a bimodal curve as well)
> 
> It is little difficult to explain to I actually created a sample figure:
> 
> http://www.flickr.com/photos/nahrenmascarenhas/6771369071/in/photostream
> 
> Any help or trick will be very useful
> loads of thanks
> 
> nahren
> 

I took some of the code that I use regularly and came up with this minimal
example of fitting data very similar to the figure you showed above. I hope
the explanations in the code are clear enough.

https://sites.google.com/site/theodoregoetz/notes/fittingaprofilein2dhistogramdata
link to my website with code example 

Here is the code and the output figure. Hope this helps someone!
Johann.

http://old.nabble.com/file/p33231288/y_profile.py y_profile.py 
http://old.nabble.com/file/p33231288/y_profile.png 




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View this message in context: http://old.nabble.com/histogram-plots-color-range-tp33215265p33231288.html
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On Mon, Jan 30, 2012 at 12:32 PM, Daryl Herzmann <ak...@ia...>wrote:

> On Sun, Jan 29, 2012 at 10:10 PM, C M <cmp...@gm...> wrote:
> > If I use the DateFormatter, like this:
> >
> > mydateformatter =
>
> >
> > I'll get dates like (note the time part):
> >
> > Nov 27 2011
> >  03:00 PM
> >
> > Instead, I'd like to lose the zero on times, like:
> >
> > Nov 27 2011
> >   3:00 PM
> >
> > Is there a way to do that?
>
> I believe if you put a '-' sign in there, it will work
>
> DateFormatter("%b%d \n %-I:%M%p", self._tz)
>
> daryl
>

Thanks, but that doesn't work.  If I use that, I get all times listed as
1:00 AM.

Che

On Sun, Jan 29, 2012 at 10:10 PM, C M <cmp...@gm...> wrote:
> If I use the DateFormatter, like this:
>
> mydateformatter =

>
> I'll get dates like (note the time part):
>
> Nov 27 2011
>  03:00 PM
>
> Instead, I'd like to lose the zero on times, like:
>
> Nov 27 2011
>   3:00 PM
>
> Is there a way to do that?

I believe if you put a '-' sign in there, it will work

DateFormatter("%b%d \n %-I:%M%p", self._tz)

daryl

On 1/30/12 3:50 PM, Fabien Lafont wrote:
> Hello,
>
> Do somebody knows how to keep only the x first terms of a numpy 1D array?
>
> like
>
> a = array([8,4,5,7,9])
> function(a,2)
>>>> [8,4]

These questions belong on the numpy mailing list. You have already asked this 
question on scipy-user and received a correct answer.

   http://www.scipy.org/Mailing_Lists

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

Hello,

Do somebody knows how to keep only the x first terms of a numpy 1D array?

like

a = array([8,4,5,7,9])
function(a,2)
>>> [8,4]

David Craig :
> Hi, thanks for that. I've made the following changes:
>
> NFFT = 100*60*10        # Linked to window size
> Fs = stream[0].stats.sampling_rate
> win = np.hanning(NFFT)
> overlap = NFFT/2
> power, freq = plt.psd(data, NFFT, Fs, win, overlap)
>
> but it returns the following error:
>
> Traceback (most recent call last):
>   File "/home/davcra/Desktop/python_scripts/welchPSD.py", line 20, in 
> <module>
>     power, freq = plt.psd(data, NFFT, Fs, win, overlap)
>   File "/usr/lib/python2.7/site-packages/matplotlib/pyplot.py", line 
> 2322, in psd
>     ret = ax.psd(x, NFFT, Fs, Fc, detrend, window, noverlap, pad_to, 
> sides, scale_by_freq, **kwargs)
>   File "/usr/lib/python2.7/site-packages/matplotlib/axes.py", line 
> 7876, in psd
>     sides, scale_by_freq)
>   File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 
> 389, in psd
>     scale_by_freq)
>   File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 
> 419, in csd
>     noverlap, pad_to, sides, scale_by_freq)
>   File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 
> 268, in _spectral_helper
>     thisX = windowVals * detrend(thisX)
> TypeError: 'int' object is not callable

Please, look the syntax of .psd in
http://matplotlib.sourceforge.net/api/pyplot_api.html?highlight=psd#matplotlib.pyplot.psd

You will find, for example, that the 5th argument, detrend, should be 
callable. In your code it is just a number.
Use explicit keywords, it may save you from misunderstanding yourself...

Jerzy Karczmarczuk

OH.
Fabrice Silva found it as well. OK, two is better than one...

Le lundi 30 janvier 2012 à 13:34 +0000, David Craig a écrit :
> Hi, thanks for that. I've made the following changes:
> 
> NFFT = 100*60*10        # Linked to window size
> Fs = stream[0].stats.sampling_rate
> win = np.hanning(NFFT)
> overlap = NFFT/2
> power, freq = plt.psd(data, NFFT, Fs, win, overlap)
> 
> but it returns the following error:
> 
> Traceback (most recent call last):
>   File "/home/davcra/Desktop/python_scripts/welchPSD.py", line 20, in <module>
>     power, freq = plt.psd(data, NFFT, Fs, win, overlap)
>   File "/usr/lib/python2.7/site-packages/matplotlib/pyplot.py", line 2322, in psd
>     ret = ax.psd(x, NFFT, Fs, Fc, detrend, window, noverlap, pad_to, sides, scale_by_freq, **kwargs)
>   File "/usr/lib/python2.7/site-packages/matplotlib/axes.py", line 7876, in psd
>     sides, scale_by_freq)
>   File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 389, in psd
>     scale_by_freq)
>   File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 419, in csd
>     noverlap, pad_to, sides, scale_by_freq)
>   File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 268, in _spectral_helper
>     thisX = windowVals * detrend(thisX)
> TypeError: 'int' object is not callable

Please be careful with argument order. Expected arguments for psd are
- the data array
- the NFFT value
- the sampling frequency
- the detrend callable (*missing in your example*)
- and then the overlap number

You should either specify on of the detrend pylab functions
(detrend_none, detrend_mean, and detrend_linear) or use keyword
arguments as I did in the example. 

-- 
Fabrice Silva

Hi, thanks for that. I've made the following changes:

NFFT = 100*60*10        # Linked to window size
Fs = stream[0].stats.sampling_rate
win = np.hanning(NFFT)
overlap = NFFT/2
power, freq = plt.psd(data, NFFT, Fs, win, overlap)

but it returns the following error:

Traceback (most recent call last):
  File "/home/davcra/Desktop/python_scripts/welchPSD.py", line 20, in
<module>
    power, freq = plt.psd(data, NFFT, Fs, win, overlap)
  File "/usr/lib/python2.7/site-packages/matplotlib/pyplot.py", line 2322,
in psd
    ret = ax.psd(x, NFFT, Fs, Fc, detrend, window, noverlap, pad_to, sides,
scale_by_freq, **kwargs)
  File "/usr/lib/python2.7/site-packages/matplotlib/axes.py", line 7876, in
psd
    sides, scale_by_freq)
  File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 389, in
psd
    scale_by_freq)
  File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 419, in
csd
    noverlap, pad_to, sides, scale_by_freq)
  File "/usr/lib/python2.7/site-packages/matplotlib/mlab.py", line 268, in
_spectral_helper
    thisX = windowVals * detrend(thisX)
TypeError: 'int' object is not callable


On Mon, Jan 30, 2012 at 12:13 PM, Fabrice Silva <si...@lm...>wrote:

> Le lundi 30 janvier 2012 à 11:45 +0000, David Craig a écrit :
> > Hi I have some data for a 24hr period with a sample rate of 100
> > samples/second. I want to create a power spectrum using matplotlibs
> > function psd. I want it to have 10 minute windows with a 50% overlap,
> > but cant seem to get the syntax right. My code is as follows:
> >
> > NFFT = len(data)
> > Fs = 100
> > window=np.hanning(Fs*60*10)
> > noverlap = window*0.5
> > plt.psd(data, NFFT, Fs, window, noverlap )
> >
> > anyone kow how to do this properly???
>
> Be careful to use a suitable value for NFFT. It must be linked to your
> windows size, not the total data length, and you would rather use a
> power of 2 for efficience. Do not use it to increase the frequency
> resolution (use pad_to instead).
>
> Fs = 100
> NFFT = Fs*60*10
> Pxx, f = plt.psd(data, NFFT, Fs, window=np.hanning(NFFT), NFFT/2)
>
> --
> Fabrice Silva
>
>
>
> ------------------------------------------------------------------------------
> 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!
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> _______________________________________________
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> https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>

Le lundi 30 janvier 2012 à 11:45 +0000, David Craig a écrit :
> Hi I have some data for a 24hr period with a sample rate of 100
> samples/second. I want to create a power spectrum using matplotlibs
> function psd. I want it to have 10 minute windows with a 50% overlap,
> but cant seem to get the syntax right. My code is as follows:
> 
> NFFT = len(data)
> Fs = 100
> window=np.hanning(Fs*60*10)
> noverlap = window*0.5
> plt.psd(data, NFFT, Fs, window, noverlap )
> 
> anyone kow how to do this properly???

Be careful to use a suitable value for NFFT. It must be linked to your
windows size, not the total data length, and you would rather use a
power of 2 for efficience. Do not use it to increase the frequency
resolution (use pad_to instead).

Fs = 100
NFFT = Fs*60*10
Pxx, f = plt.psd(data, NFFT, Fs, window=np.hanning(NFFT), NFFT/2)

-- 
Fabrice Silva

Hi I have some data for a 24hr period with a sample rate of 100
samples/second. I want to create a power spectrum using matplotlibs
function psd. I want it to have 10 minute windows with a 50% overlap, but
cant seem to get the syntax right. My code is as follows:

NFFT = len(data)
Fs = 100
window=np.hanning(Fs*60*10)
noverlap = window*0.5
plt.psd(data, NFFT, Fs, window, noverlap )

anyone kow how to do this properly???

Thanks,
D

Hi

Thank you very much, it worked perfectly :D

Kind regards

Pål

On 27 January 2012 15:29, Tony Yu <ts...@gm...> wrote:

>
>
> On Fri, Jan 27, 2012 at 9:13 AM, Pål Gunnar Ellingsen <pa...@gm...>wrote:
>
>> Hi
>>
>> I have a array, M, which is (4Nx4M), and an array (image), im, which is
>> NxM.
>> I can currently plot the matrix as a 2d image using imshow using:
>>
>> import matplotlib.pyplot as plt
>> from matplotlib import cm
>>
>> # some code for reading in the matrix
>>
>> cmap = cm.get_cmap('jet', 256)
>> imM = plt.imshow(M, cmap=cmap, vmin= -1, vmax=1)
>>
>> But now i would like to plot im on top of M, such that it covers the firs
>> element of M.
>> If I do
>>
>> plt.hold()
>> plt.imshow(im)
>>
>> I only see im, and not M. I'm used to doing this in Matlab, where this
>> would work.
>>
>> Can anyone explain me what I'm doing wrong?
>>
>>
>> Kind Regards
>>
>
> A call to `plt.autoscale` should fix your problem. It looks like `imshow`
> rescales the axes limits to the current image limits, instead of the limits
> for all the data in the axes. (Executable example below; note, axes "hold"
> by default, so it's not necessary to call hold).
>
> -Tony
>
>
>
> import numpy as np
> import matplotlib.pyplot as plt
>
> background = np.random.uniform(0, 255, size=(20, 20))
> overlay = np.arange(25).reshape((5, 5))
>
> plt.imshow(background, interpolation='nearest', cmap=plt.cm.gray)
> plt.imshow(overlay, cmap=plt.cm.jet, alpha=0.5)
> # You could also replace this with `plt.axis([0, 20, 0, 20])
> plt.autoscale()
> plt.show()
>

If I use the DateFormatter, like this:

mydateformatter = DateFormatter("%b%d \n %I:%M%p", self._tz)

I'll get dates like (note the time part):

Nov 27 2011
 03:00 PM

Instead, I'd like to lose the zero on times, like:

Nov 27 2011
  3:00 PM

Is there a way to do that?

Thanks,
Che

On Wed, Jan 4, 2012 at 2:19 PM, Benjamin Root <ben...@ou...> wrote:

>
>
> On Wednesday, January 4, 2012, jeffsp <je...@gm...> wrote:
> >
> > plt.tight_layout(), sweet
> >
> > it still makes the labels too close to read, even if they don't overlap.
> > that is, they're just a continuous string of numbers with no whitespace
> > between.
> >
> > it does clean up the rest of the plot really nicely, though, without
> having
> > to continually dick around with subplots_adjust
> >
> >
>
> Well, it is a new feature with plenty of room for improvements.  Maybe
> some sort of mindist parameter would be useful to establish a minimum
> distance between text objects?
>
> Ben Root
>
>
Something like that sounds good.  If there were a way to make it the
default that labels would never overlap (but that default could be toggled
for those who, somehow, want to not be able to read their labels?), that
strikes me as best.

In the meantime, what are other ways to do this?