matplotlib-users Mailing List for matplotlib

> To: Nils Wagner <nw...@me...>
> Cc: SciPy Users List <sci...@sc...>,
> 	mat...@li...
> Subject: Re: [Matplotlib-users] Visualizing Sparsity Pattern of matrices
> From: John Hunter <jdh...@ac...>
> Date: Thu, 11 Nov 2004 09:16:03 -0600
> 
> 
>>>>>>"Nils" == Nils Wagner <nw...@me...> writes:
> 
> 
>     Nils> Hi all, Structure plots provide a quick visual check on the
>     Nils> sparsity pattern of the matrix.  A structure plot is a
>     Nils> rectangular array of dots; a dot is black if the
>     Nils> corresponding matrix element is nonzero otherwise it is
>     Nils> white.
> 
>     Nils> Is it possible to generate such plots with scipy or should
>     Nils> we switch over to matplotlib ?
> 
> Here's another implementation that uses images - likely to be much
> faster for very large matrices.

Hi,

As part of a programming environment for optimization in Python (soon to 
be released hopefully), I use Matplotlib for the graphics. I created 
several functions imitating Matlab's spy() using scatter(). My sparse 
matrices are represented in linked-list, compressed column or compressed 
row storage using the PySparse implementation
	http://people.web.psi.ch/geus/pyfemax/pysparse.html

Using scatter, I can plot the sparsity pattern of matrices with several 
thousands of lines and columns in a blink on my 1.7GHz P4 laptop. Using 
color maps, you can even color your dots according to the magnitude of 
the element they represent (a 2-dimensional "city plot" of a matrix).

Dominique

>>>>> "Dimitri" == Dimitri D'Or <dim...@fs...> writes:

    Dimitri> Hello, I would like to know if there is a mean for
    Dimitri> testing on the hold status of a figure, i.e. to know if
    Dimitri> hold is 'on' or 'off' ?

    Dimitri> In fact, I use frequently the ISHOLD function in Matlab
    Dimitri> and I can't find a similar one in Matplotlib.

A sin of omission.  I just added it to CVS.  If you don't have CVS
access, in the meantime, you can either use the ax._ishold variable to
inspect the axes hold status, or add the following

to matplotlib.axes.Axes:

    def ishold(self):
        'return the HOLD status of the axes'
        return self._hold

and to matplotlib.matlab

    def ishold(b=None):
       """
       Return the hold status of the current axes
       """
       return gca().ishold()    

Should cure what ails ya ...

JDH

>>>>> "Shin" == Shin  <sd...@em...> writes:

    Shin> Currently, figure() is the same as figure(1).  But, I think
    Shin> a better behavior of figure is: figure() is the same as
    Shin> figure(n+1) where n is the maximum handle number of opened
    Shin> figures. So, figure() always creates a new figure.  This is
    Shin> exactly MATLAB is doing.  Any comment?

Looks like a bug - thanks.

Is anybody relying on the fact the figure() currently returns the
current figure if it exists?  This is basically the role of gcf,
anyway, which creates a figure none exists and returns it, otherwise
it returns the current figure.

So figure should auto-increment, as you suggest.

JDH

>>>>> "Shin" == Shin  <sd...@em...> writes:

    Shin> Thanks. Let me ask another question.  How can I get the
    Shin> current mode?  I like to recover mode after drawing
    Shin> everything in non-interactive mode.  From help document,
    Shin> interactive() seems not to give current mode.

>>> from matplotlib import interactive, is_interactive
>>> print is_interactive()
False

Sorry that these features aren't documented :-(

By the way, ipython already has all of this built-in.  In the pylab
mode you start in interactive mode.  But you can "run" a code snippent
using the run command, which turns off interactive mode for the
duration of the run, restoring the original interactive state when the
run finishes.

JDH

Hello,

I would like to know if there is a mean for testing on the hold status of a 
figure, i.e. to know if hold is 'on' or 'off' ?

In fact, I use frequently the ISHOLD function in Matlab and I can't find a 
similar one in Matplotlib.

Thank you,

Dimitri

Currently, figure() is the same as figure(1).
But, I think a better behavior of figure is:
figure() is the same as figure(n+1) where n is the maximum handle number 
of opened figures. So, figure() always creates a new figure.
This is exactly MATLAB is doing.
Any comment?

Daehyok Shin
UNC-CH

Thanks. Let me ask another question.
How can I get the current mode?
I like to recover mode after drawing everything in non-interactive mode.
 From help document, interactive() seems not to give current mode.

Daehyok Shin

John Hunter wrote:

> 
> from matplotlib import interactive
> from matplotlib.matlab import *
> 
> plot([1,2,3])
> interactive(False)  # turn off interactive mode
> xlabel('hi mom')
> ylabel('bye')
> title('all done')
> interactive(False)  # turn it back on
> draw()              # draw the canvas
> 
> JDH
> 
> 
> 
> 
> 
> 
> 
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