matplotlib-users Mailing List for matplotlib (Page 2)

Hi Dr. Pessenhofer,

On Wednesday 27 April 2005 4:12 am, Dr. Werner Pessenhofer wrote:
> ____________________________________________________
>
> #!/usr/bin/python
> #-*- coding: UTF-8 -*-
>
>  from pylab import *
>
> X = load('Spektren-CuP-conv.dat',comments='#')
>
> hold(True)
>
> xlabel(r'$\rm{Wellenl\"ange / nm}$')
> ylabel('Extinktion')
> title('Spektren CuP')
>
> ind = 1
> while ind < 18:
>      Y = take(X,(0,ind), 1)
>      x = Y[:,0]
>      y = Y[:,1]
>      plot(x,y,'-')
>      ind = ind + 2
>
> savefig("Spektren-CuP.ps",orientation="landscape")
>
> show()
> ________________________________________________________
>
> The first problem is, that all curves have the same color. Is there a
> possibility to "rotate" the colors in the loop ?

You could change plot(x,y,'-') to  plot(x,y). It will default to the '-' 
linestyle, and matplotlib will cycle the colors for you. Also, the examples 
include a script called line_styles.py with this suggestion:


>
> Second question:
>
> With savefig("Spektren-CuP.ps",orientation="landscape"), the diagram do
> not fill the whole a4 page. I think, this is related to some configuration
> values, cause the resulting figure is not an a4 page but a BBox. Any hints
> where to change that ?
>
> Regards
>
> Werner

-- 
Darren S. Dale

Bard Hall
Department of Materials Science and Engineering
Cornell University
Ithaca, NY. 14850

dd...@co...

Hi all,

I'm using matplotlib and Numeric since a few days ago, so I am not very =20
sophisticated in using python :-)

I want to use matplotlib to print automatically several spectras from a =20
file. This means, it takes the first column as x-value and the second, =20
fourth, sixth .... column as y-value.

The script I wrote:

____________________________________________________

#!/usr/bin/python
#-*- coding: UTF-8 -*-

 from pylab import *

X =3D load('Spektren-CuP-conv.dat',comments=3D'#')

hold(True)

xlabel(r'$\rm{Wellenl\"ange / nm}$')
ylabel('Extinktion')
title('Spektren CuP')

ind =3D 1
while ind < 18:
     Y =3D take(X,(0,ind), 1)
     x =3D Y[:,0]
     y =3D Y[:,1]
     plot(x,y,'-')
     ind =3D ind + 2

savefig("Spektren-CuP.ps",orientation=3D"landscape")

show()
________________________________________________________

The first problem is, that all curves have the same color. Is there a =20
possibility to "rotate" the colors in the loop ?

Second question:

With savefig("Spektren-CuP.ps",orientation=3D"landscape"), the diagram do=
 =20
not fill the whole a4 page. I think, this is related to some configuratio=
n =20
values, cause the resulting figure is not an a4 page but a BBox. Any hint=
s =20
where to change that ?

Regards

Werner


--=20
DI Dr. Werner Pessenhofer

CPA - Computer Process Automation
Pl=FCddemanngasse 33
8010 Graz
Tel.: +43 (0) 676 346 70 08
FAX: +43 (0) 316 873 8772

Hi,
I recently sent a mail to matplotlib-users regarding the availability of 
3 axes plots and histograms in 2/N D and got no feedback.
I understand this may  not be a very exciting issue but if anybody has 
any input there (see below), it would be welcome. Thanks in advance!!

cheers

Eric
=============================================
3 axes plot
========
The more I am using matplotlib, the more I like it. But using it more 
means I more often hit the limits of the code, so I was wondering if 
there is any plan for a routine to plot data points w.r.t 3 axes (so a 
perspective scatter plot with x,y,z, data and a viewing angle). Of 
course another (maybe more difficult) goal would be to be able to draw 
surfaces, but already a simple scatter plot in 3D would help 
tremendously there (I realize the concept of "axis" has then to be 
revised, but well I have no idea how much effort this is).

(if there is no - coming - plan for this, is there any way around it?)

histograms
========
I would like to produce histograms in N dimensions, the minimum being in 
2D.
Here is an example of what I wish to do:

I have a set of P particles with x and y positions.
I have a rectangular grid, defined by e.g. a sampling in x and a 
sampling in y, (e.g. samp_x=arange(-15,31,1) ..), and I wish to know how 
many particles are in each "pixel".

I can do that in many different ways (using searchsorted from numarray, 
or abruptly using loops, etc) but I am now looking for a simple (fewer 
lines) and efficient way (as I am treating large sets of particles) to 
do this so that I would be able to use a function like:

histogram_2D(x,y, samp_x, samp_y) would return a matrix with the number 
of particles in each corresponding pixel.

and

showhistogram_2D(x,y, samp_x, samp_y) would display it
[using e.g. imshow or matshow]

Any hint there (I realize this is more a numarray question but I thought 
of first asking your community first since someone may have done it 
already)? And maybe also of how to generalize this in N dimensions? (for 
1D matplotlib has the hist function..)

-- 
===============================================================
Observatoire de Lyon                 ems...@ob...
9 av. Charles-Andre                      tel: +33 4 78 86 83 84
69561 Saint-Genis Laval Cedex            fax: +33 4 78 86 83 86
France               http://www-obs.univ-lyon1.fr/eric.emsellem
===============================================================

>>>>> "Karsten" == Karsten Wedel Jacobsen <kw...@fy...> writes:

    Karsten> After that the build and install went smoothly. But now
    Karsten> if I try to import pylab I get the following error:
    Karsten> pixbuf_get_pixels_array ImportError: No module named
    Karsten> _nc_backend_gdk

    Karsten> As far as I can see it is still trying to use some
    Karsten> gtk-stuff?

This is a bit of annoyance in the mpl setup.  The backend that is
chosen at runtime is determined by the rc file (see
http://matplotlib.sf.net/.matplotlibrc) and the default backend in the
rc file is GTKAgg.  Even if you turn GTK compilation off in setup.py,
the rc file still determines which backend is selected.  You need to
copy that file from its default location (eg
/usr/share/matplotlib/.matplotlibrc) to your HOME directory and edit
the 'backend' setting to something else, eg TkAgg, WXAgg or QtAgg.

While debugging, it is helpful to create a simple script like

  import pylab
  pylab.plot([1,2,3])
  pylab.show()

and run it with 

  > python myscript.py --verbose-helpful

which will show you which rc file is being loaded, which backend is
selected, what mpl version you are using, and so on.


Should help,
JDH

PS: the bug in pygtk2.4 in fedora core 3 is quite ease to fix.  You
simply have to replace typename with another name like typename_ or
some other name as described in the FAQ.