matplotlib-users Mailing List for matplotlib

On Fri, Jan 27, 2012 at 10:06 AM, Howard <ho...@re...> wrote:

>  On 1/27/12 3:39 AM, Ian Thomas wrote:
>
> On 26 January 2012 19:36, Howard <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

On Fri, Jan 27, 2012 at 4:54 AM, Jerzy Karczmarczuk <
jer...@un...> wrote:

> Benjamin Root answers my query concerning user-generated events :
> > To answer your question, take a look at how pick_event() is declared
> > in backend_bases.py:
> >
> >     def pick_event(self, mouseevent, artist, **kwargs):
> >      ...
> >         self.callbacks.process(s, event)
> >
> > The function that "fires" the event is "self.callbacks.process(s,
> > event)", where "self" is the figure canvas.
> Dear Ben, thank you, but this is not exactly my problem. I don't want to
> call the callback myself, since the event should be "fired" from within
> a callback. I should have been more precise. Let's distil the problem.
> [This is a part of my current teaching...] I did already what you
> suggest here...
>
> Imagine an animation, which consists in generating a trajectory, segment
> after segment (say, of a planet). Classically this is a loop, but when
> it runs, the rest of the program is blocked. So, instead, the code
> behaves as a Python generator, generates just one segment, and that's
> all. But it "yields" something, it posts an event, put it in a queue,
> and somebody else, the mainloop() or similar, pops it off the queue and
> re-launches the callback. (With generators, it calls the .next()). No
> timers, as in Timer or Funct animations...
>
> It must be "decentralized", no recursive calls. My callback from time to
> time creates another planet, or destroys an existent, and there are
> simultaneous trajectories on the screen, several concurrent events in
> the queue. And the system should remain reactive, interpret buttons,
> sliders, etc.
>
> I know how to do this by hand, how to write my own event loop, declare a
> queue, and how to add to my private "virtual" event handling also the
> callbacks of mouse events. But this is an overkill, I  repeat the
> functionalities which are already there, the event queue in particular.
>
> I did it with wx. But Matplotlib protects the user from the concrete
> back-end, and I want to protect my students as well, so I look for a
> "GUI-neutral" solution.
>
> Thanks.
>
> Jerzy
>
>
Still not sure why my suggestion would not work:

http://matplotlib.sourceforge.net/api/cbook_api.html#matplotlib.cbook.CallbackRegistry

You can have things set up such that event being triggered can subsequently
trigger other events as well.  An event can even connect a new event as
well.  An example where I do this is when I want to hide a line while it is
clicked.  In the function that I connect to a "button_press_event", I make
the artist invisible, and I also create a lambda function that sets the
visibility of that artist to True (and subsequently disconnects itself) and
connect that lambda to a "button_release_event".

Keep in mind that these "events" are merely key'ed by strings like
"button_press_event", there is nothing magical about them.  So, when you
call the .process() function with a string value and an Event object, it
passes that object to every connection that was made with that same string
value.  You can call the process() function from anywhere, even within an
event.

Now, I haven't tried connecting a generator function with a yield statement
before, so I don't know how well that would work, but I don't know why it
wouldn't.

Why exactly would the callback registry not work for you?

Ben Root

Tony Yu suggests that my multiple and changing animation problems could 
be solved using coroutining.
> have you looked into using a coroutine. /... /I've attached a simple 
> example below.
>
> import matplotlib.pyplot as plt
> import numpy as np
> def datalistener():
> ...
>     while True:
>         y0 = yield
>         x = np.hstack((line.get_xdata(), i))
>   ...
> plt.ion()
> ...
Thank you Tony. No, unfortunately this is again a "side solution". Of 
course, coroutines, or just a simple event loop using Python generators 
without .send(), are perfectly decent tools to simulate parallel 
"movements". But, coroutines as such, are better adapted to situations 
where the actors transfer the control among themselves, where there is a 
network of direct communications, a "multi-ping-pong".
In my case this is redundant, my "planets" which move concurrently are 
independent, and they, after having updated their properties, need only 
to yield the control to the interface, to draw them. The interface 
resumes (by calling, no .send() is needed) all the actors in sequence. I 
repeat again : I COULD have written my own event loop (under ion()).

But I don't want to do this, since show() which calls some lower level 
mainloop() does all this already!

In particular, it handles the physical events, all mousing, which need 
anyway some lower-level mechanisms, and my own coroutines won't help. I 
MUST use the built-in tools in order to handle the mouse.

So, I repeat, my only [as I see it] rational choice is to plug-in my 
events into the standard loop. Under, say, plain wxPython, I can write 
my own, and call ProcessPendingEvents(), but with Matplotlib, no idea.
Ben Root  suggested to look some existing codes, say the Picker. But 
this is called upon a physical event, which is "fired" under the hood. 
My events are "virtual", I have to post them myself from a callback, so 
it canot call recursively another callback, or I am dead.

Best regards.

Jerzy

On Fri, Jan 27, 2012 at 4:01 PM, <jos...@gm...> wrote:

> On Fri, Jan 27, 2012 at 12:18 PM, Tony Yu <ts...@gm...> wrote:
> >
> >
> > On Fri, Jan 27, 2012 at 11:27 AM, nahren manuel <mee...@ya...>
> > 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
> >
> >
> > This plot seems similar to something I wanted to do (and asked the list
> > about). I ended up getting something to work, but the code is a bit ugly.
> > I've attached my most recent version (which probably needs some cleaning
> up,
> > but it works).
> >
> > If you want a continuous field instead of distinct bars (like you have in
> > your sample image), you may be able to write up something that's a little
> > simpler by sectioning out the columns an array into strips of equal width
> > and repeating histogram values across those columns (sorry, this is a bit
> > vague). Then use `imshow` to plot the array.
>
> Looks nice.
>
> Given that it is too specialized for matplotlib, it would be an
> interesting addition to violin and bean plots in scikits.statsmodels
> if you don't mind that we borrow it (scikits.statsmodels is BSD
> licensed).
>
> Thanks,
>
> Josef
>
>
Sure thing---I'm happy to contribute. The code probably needs to be cleaned
up, but unfortunately, I have little motivation since I don't use it
anymore. Feel free to do whatever you like with it.

Cheers,
-Tony

On Fri, Jan 27, 2012 at 12:18 PM, Tony Yu <ts...@gm...> wrote:
>
>
> On Fri, Jan 27, 2012 at 11:27 AM, nahren manuel <mee...@ya...>
> 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
>
>
> This plot seems similar to something I wanted to do (and asked the list
> about). I ended up getting something to work, but the code is a bit ugly.
> I've attached my most recent version (which probably needs some cleaning up,
> but it works).
>
> If you want a continuous field instead of distinct bars (like you have in
> your sample image), you may be able to write up something that's a little
> simpler by sectioning out the columns an array into strips of equal width
> and repeating histogram values across those columns (sorry, this is a bit
> vague). Then use `imshow` to plot the array.

Looks nice.

Given that it is too specialized for matplotlib, it would be an
interesting addition to violin and bean plots in scikits.statsmodels
if you don't mind that we borrow it (scikits.statsmodels is BSD
licensed).

Thanks,

Josef

>
> -Tony
>
>
>
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On Fri, Jan 27, 2012 at 5:54 AM, Jerzy Karczmarczuk <
jer...@un...> wrote:

> Benjamin Root answers my query concerning user-generated events :
> > To answer your question, take a look at how pick_event() is declared
> > in backend_bases.py:
> >
> >     def pick_event(self, mouseevent, artist, **kwargs):
> >      ...
> >         self.callbacks.process(s, event)
> >
> > The function that "fires" the event is "self.callbacks.process(s,
> > event)", where "self" is the figure canvas.
> Dear Ben, thank you, but this is not exactly my problem. I don't want to
> call the callback myself, since the event should be "fired" from within
> a callback. I should have been more precise. Let's distil the problem.
> [This is a part of my current teaching...] I did already what you
> suggest here...
>
> Imagine an animation, which consists in generating a trajectory, segment
> after segment (say, of a planet). Classically this is a loop, but when
> it runs, the rest of the program is blocked. So, instead, the code
> behaves as a Python generator, generates just one segment, and that's
> all. But it "yields" something, it posts an event, put it in a queue,
> and somebody else, the mainloop() or similar, pops it off the queue and
> re-launches the callback. (With generators, it calls the .next()). No
> timers, as in Timer or Funct animations...
>
> It must be "decentralized", no recursive calls. My callback from time to
> time creates another planet, or destroys an existent, and there are
> simultaneous trajectories on the screen, several concurrent events in
> the queue. And the system should remain reactive, interpret buttons,
> sliders, etc.
>
> I know how to do this by hand, how to write my own event loop, declare a
> queue, and how to add to my private "virtual" event handling also the
> callbacks of mouse events. But this is an overkill, I  repeat the
> functionalities which are already there, the event queue in particular.
>
> I did it with wx. But Matplotlib protects the user from the concrete
> back-end, and I want to protect my students as well, so I look for a
> "GUI-neutral" solution.
>
> Thanks.
>
> Jerzy
>

I'm not sure if this matches your use case, but have you looked into using
a coroutine. (I only recently learned about them---see presentation slides
linked on this page <http://www.dabeaz.com/coroutines/>. So obviously I'm
going out of my way to find a use case :)

I've attached a simple example below.

-Tony

#~~~

import matplotlib.pyplot as plt
import numpy as np


def datalistener():
    fig, ax = plt.subplots()
    line, = ax.plot(0, 0, 'o-')
    i = 1
    while True:
        y0 = yield
        x = np.hstack((line.get_xdata(), i))
        y = np.hstack((line.get_ydata(), y0))
        line.set_data((x, y))
        ax.update_datalim(np.transpose((x, y)))
        ax.autoscale_view()
        plt.draw()
        i += 1


plt.ion()
plotdata = datalistener()
# initialize the coroutine
plotdata.next()
while True:
    y = raw_input('enter data point: ')
    try:
        plotdata.send(float(y))
    except:
        break

On Jan 27, 2012, at 9:11 AM, Fabien Lafont wrote:

> Ive tried:
> 
> for i in range(0,NbPts):
>    if column1[i] == nan:
>        column1[i].remove(nan)
>        column2[i].remove(nan)
> 
> to remove these points but it doesn't work
> 

you are close, I think what you want is: 

# assuming column1 and 2 are numpy arrays
import numpy as np

for i in range(0,NbPts):
   if np.isnan(column1[i]):
       column1=np.remove(column1,i,0)
       column1=np.remove(column2,i,0)

> 
> 2012/1/27 Benjamin Root <ben...@ou...>:
>> On Fri, Jan 27, 2012 at 9:52 AM, Fabien Lafont <laf...@gm...>
>> wrote:
>>> 
>>> Sorry, It's an awkward manipulation. I finish the mail
>>> 
>>> 2012/1/27 Fabien Lafont <laf...@gm...>:
>>>> I want to plot something like:
>>>> 
>>>> 
>>>> X(time)        Ypoints
>>>> 0                    8
>>>> 1
>>>> 2                    7
>>>> 3                    6
>>>> 4                    4
>>>> 5
>>>> 6
>>>> 7                    7
>>>> 8                    2
>>>> 9                   10
>>> 
>>> In fact I've recorded some live datas and when I use genfromtxt() the
>>> blank parts are "translated" as 'nan' and I can't for example fit it
>>> with polynomials.
>>> 
>> 
>> If you plot the data, it should skip data points that are NaNs and you
>> should see a break in the line IIRC.  Is that not what you want?
>> 
>> 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!
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> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users

Thanks a lot, I'll try to remove the points using isnan()

2012/1/27 Fabrice Silva <si...@lm...>:
> What about masked arrays ?
> http://docs.scipy.org/doc/numpy/reference/maskedarray.html
>
>
> --
> 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!
> http://p.sf.net/sfu/learndevnow-dev2
> _______________________________________________
> Matplotlib-users mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-users

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

What about masked arrays ?
http://docs.scipy.org/doc/numpy/reference/maskedarray.html


-- 
Fabrice Silva

On Fri, Jan 27, 2012 at 10:11 AM, Fabien Lafont <laf...@gm...>wrote:

> Yes in fact it plot it well, but then I have a vector like:
> [3702.1399999999999, nan, nan, nan, 3703.79, nan, nan, nan,
> 3704.6900000000001, 3704.8400000000001]
> and it's impossible to fit it. It return 'nan'.
>
> Ive tried:
>
> for i in range(0,NbPts):
>    if column1[i] == nan:
>        column1[i].remove(nan)
>        column2[i].remove(nan)
>
> to remove these points but it doesn't work
>
>
You can't do equality tests with NaNs (us np.isnan(), instead).  This
question is more suited for the Numpy list.

Ben Root

Fri, 27 Jan 2012 16:48:25 +0100
Fabien Lafont a écrit:

> I want to plot something like:
> 
> 
> X(time)        Ypoints
> 0                    8
> 1
> 2                     7
> 3
> 4
> 5
> 6
> 7
> 8
> 9

Sorry if I'm missing something, but can't you plot Y [8,7] against X [0,2] ?

-- 
Jérôme

Dear Users,
I want to plot a XY, the X-value is constant, but let assume Y varees 
from 1-10, so I want o have different colors accordingly for the range 
0-2,2-4,4-6,6-8,8-10.

thanks a lot
najren

Yes in fact it plot it well, but then I have a vector like:
[3702.1399999999999, nan, nan, nan, 3703.79, nan, nan, nan,
3704.6900000000001, 3704.8400000000001]
and it's impossible to fit it. It return 'nan'.

Ive tried:

for i in range(0,NbPts):
    if column1[i] == nan:
        column1[i].remove(nan)
        column2[i].remove(nan)

to remove these points but it doesn't work


2012/1/27 Benjamin Root <ben...@ou...>:
> On Fri, Jan 27, 2012 at 9:52 AM, Fabien Lafont <laf...@gm...>
> wrote:
>>
>> Sorry, It's an awkward manipulation. I finish the mail
>>
>> 2012/1/27 Fabien Lafont <laf...@gm...>:
>> > I want to plot something like:
>> >
>> >
>> > X(time)        Ypoints
>> > 0                    8
>> > 1
>> > 2                    7
>> > 3                    6
>> > 4                    4
>> > 5
>> > 6
>> > 7                    7
>> > 8                    2
>> > 9                   10
>>
>> In fact I've recorded some live datas and when I use genfromtxt() the
>> blank parts are "translated" as 'nan' and I can't for example fit it
>> with polynomials.
>>
>
> If you plot the data, it should skip data points that are NaNs and you
> should see a break in the line IIRC.  Is that not what you want?
>
> Ben Root
>

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

-- 
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

On Fri, Jan 27, 2012 at 9:52 AM, Fabien Lafont <laf...@gm...>wrote:

> Sorry, It's an awkward manipulation. I finish the mail
>
> 2012/1/27 Fabien Lafont <laf...@gm...>:
> > I want to plot something like:
> >
> >
> > X(time)        Ypoints
> > 0                    8
> > 1
> > 2                    7
> > 3                    6
> > 4                    4
> > 5
> > 6
> > 7                    7
> > 8                    2
> > 9                   10
>
> In fact I've recorded some live datas and when I use genfromtxt() the
> blank parts are "translated" as 'nan' and I can't for example fit it
> with polynomials.
>
>
If you plot the data, it should skip data points that are NaNs and you
should see a break in the line IIRC.  Is that not what you want?

Ben Root

Sorry, It's an awkward manipulation. I finish the mail

2012/1/27 Fabien Lafont <laf...@gm...>:
> I want to plot something like:
>
>
> X(time)        Ypoints
> 0                    8
> 1
> 2                    7
> 3                    6
> 4                    4
> 5
> 6
> 7                    7
> 8                    2
> 9                   10

In fact I've recorded some live datas and when I use genfromtxt() the
blank parts are "translated" as 'nan' and I can't for example fit it
with polynomials.

I want to plot something like:


X(time)        Ypoints
0                    8
1
2                     7
3
4
5
6
7
8
9

On Friday, January 27, 2012, Eric Emsellem <eem...@es...> wrote:
> Dear all,
>
> I have a set of Voronoi bins, defined by nodes (x,y) and an underlying
> mesh of squared bins.
> See an example here of such Voronoi bins.
>
>
http://www.google.fr/imgres?q=voronoi+binning&hl=fr&sa=X&biw=1280&bih=665&tbm=isch&prmd=imvnsb&tbnid=zp0RRIktKlF9pM:&imgrefurl=http://www.aanda.org/articles/aa/full/2007/09/aa4621-05/aa4621-05.right.html&docid=CeAk6FN_pZDa5M&imgurl=http://www.aanda.org/articles/aa/full/2007/09/aa4621-05/img26.gif&w=532&h=1087&ei=ZmYiT-Z7xYDyA9ew0acM&zoom=1&iact=rc&dur=164&sig=112304340793152029504&page=4&tbnh=151&tbnw=74&start=63&ndsp=25&ved=1t:429,r:1,s:63&tx=58&ty=65
>
> So basically each node, (x,y) would define a Voronoi bin made of a set
> of squared pixels. So one node would correspond to for example N squared
> pixels:
>
> node[i] = [(x1,y1),(x2,y2),...(xN,yN)]
>
> I want now to create an imshow like plot of these bins by using the four
> colour theorem, meaning that I would use 4 colours and want adjacent
> Voronoi bins not to have the same colour.
>
> Is there a simple way to do this in matplotlib? I couldn't find much on
> the web so far.
>
> thanks!
> Eric
>

None that I am aware of, but if one existed, it would likely be found
within the basemap module.  If it isn't in the Basemap module, it would be
an awesome feature to add.  Maybe something that would work with my
style-cycling mechanism that I have been tinkering with to allow for users
to specify 4 different hatchings for b&w publications?

Cheers!
Ben Root

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()

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

Benjamin Root answers my query concerning user-generated events :
> To answer your question, take a look at how pick_event() is declared 
> in backend_bases.py:
>
>     def pick_event(self, mouseevent, artist, **kwargs):
>      ...
>         self.callbacks.process(s, event)
>
> The function that "fires" the event is "self.callbacks.process(s, 
> event)", where "self" is the figure canvas.
Dear Ben, thank you, but this is not exactly my problem. I don't want to 
call the callback myself, since the event should be "fired" from within 
a callback. I should have been more precise. Let's distil the problem. 
[This is a part of my current teaching...] I did already what you 
suggest here...

Imagine an animation, which consists in generating a trajectory, segment 
after segment (say, of a planet). Classically this is a loop, but when 
it runs, the rest of the program is blocked. So, instead, the code 
behaves as a Python generator, generates just one segment, and that's 
all. But it "yields" something, it posts an event, put it in a queue, 
and somebody else, the mainloop() or similar, pops it off the queue and 
re-launches the callback. (With generators, it calls the .next()). No 
timers, as in Timer or Funct animations...

It must be "decentralized", no recursive calls. My callback from time to 
time creates another planet, or destroys an existent, and there are 
simultaneous trajectories on the screen, several concurrent events in 
the queue. And the system should remain reactive, interpret buttons, 
sliders, etc.

I know how to do this by hand, how to write my own event loop, declare a 
queue, and how to add to my private "virtual" event handling also the 
callbacks of mouse events. But this is an overkill, I  repeat the 
functionalities which are already there, the event queue in particular.

I did it with wx. But Matplotlib protects the user from the concrete 
back-end, and I want to protect my students as well, so I look for a 
"GUI-neutral" solution.

Thanks.

Jerzy

Dear all,

I have a set of Voronoi bins, defined by nodes (x,y) and an underlying 
mesh of squared bins.
See an example here of such Voronoi bins.

http://www.google.fr/imgres?q=voronoi+binning&hl=fr&sa=X&biw=1280&bih=665&tbm=isch&prmd=imvnsb&tbnid=zp0RRIktKlF9pM:&imgrefurl=http://www.aanda.org/articles/aa/full/2007/09/aa4621-05/aa4621-05.right.html&docid=CeAk6FN_pZDa5M&imgurl=http://www.aanda.org/articles/aa/full/2007/09/aa4621-05/img26.gif&w=532&h=1087&ei=ZmYiT-Z7xYDyA9ew0acM&zoom=1&iact=rc&dur=164&sig=112304340793152029504&page=4&tbnh=151&tbnw=74&start=63&ndsp=25&ved=1t:429,r:1,s:63&tx=58&ty=65

So basically each node, (x,y) would define a Voronoi bin made of a set 
of squared pixels. So one node would correspond to for example N squared 
pixels:

node[i] = [(x1,y1),(x2,y2),...(xN,yN)]

I want now to create an imshow like plot of these bins by using the four 
colour theorem, meaning that I would use 4 colours and want adjacent 
Voronoi bins not to have the same colour.

Is there a simple way to do this in matplotlib? I couldn't find much on 
the web so far.

thanks!
Eric

On 26 January 2012 19:36, Howard <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

Hi Shankar,

Shankararaman Ramakrishnan, on 2012-01-26 18:24,  wrote:
> I have been trying to leverage plot_date() to generate time trends. I
> seem to run into the following runtime error and don't have much
> insight as to why this is happening. Specifically, I don't quite see why
> the function is attempting to set the lower bound to 0001-01-01 UTC when
> my x-axis starts only from day number 729390. 

I suspect this may be the case because you've already plotted
something on this axis that resolves to this early date. For
example, I can reproduce an error similar to yours by first doing
plot(1,0) before the plot_date call.

Can you try to create a new figure just before the call to plot_date?

best,
-- 
Paul Ivanov
314 address only used for lists,  off-list direct email at:
http://pirsquared.org | GPG/PGP key id: 0x0F3E28F7