matplotlib-users Mailing List for matplotlib

I'm using matplotlib master from
https://launchpad.net/%7Etakluyver/+archive/matplotlib-daily, ubuntu
12.10 and python 2.7 and sometimes I get misplaced y labels for twinx
plots. I file a bug at github with a sample script and figure images:
https://github.com/matplotlib/matplotlib/issues/1608
A guy commented there saying he can't replicate the issue. I wonder if
anyone using ubuntu 12.10 can try my code with the matplotlib version
from that repo and share the output.

Best regards

Goyo

On 9 January 2013 09:32, Shahar Shani-Kadmiel <ka...@po...>wrote:

> Hi,
>
> I'm trying to contour some data that I have and the griddata line fails. I
> tried running it on some synthetically generated data and I get the same
> IndexError. Any Ideas?
>
> Here is the example with the synthetic data:
>
> x = y = arange(-10,10,0.01)
>
> z = x**2+y**3
>
> xi = yi = linspace(-10.1, 10.1, 100)
>
> zi = griddata(x, y, z, xi, yi)
> ---------------------------------------------------------------------------
> IndexError                                Traceback (most recent call last)
> <ipython-input-52-0458ab6ea672> in <module>()
> ----> 1 zi = griddata(x, y, z, xi, yi)
>
> /Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/site-packages/matplotlib/mlab.py
> in griddata(x, y, z, xi, yi, interp)
>    2766             xi,yi = np.meshgrid(xi,yi)
>    2767         # triangulate data
> -> 2768         tri = delaunay.Triangulation(x,y)
>

Hello Shahar,

I think that your simple example is probably not what you intended.  Your
(x,y) points are all defined on the straight line from (-10,-10) to
(10,10).  The Delaunay triangulation of these points (which is what
griddata does) is not very interesting!  Perhaps you wanted (x,y) defined
on the 2D grid from (-10,-10) to (10,10), in which case you should follow
the x = y ... line with, for example:
    x, y = meshgrid(x, y)
(see numpy.meshgrid for further details).

You may still obtain the same IndexError, and the traceback shows this is
happening in the delaunay.Triangulation function call.  The matplotlib
delaunay package is not particularly robust, and can have problems handling
regularly-spaced data points.  The griddata documentation explains some of
this, see http://matplotlib.org/api/mlab_api.html#matplotlib.mlab.griddata.

To avoid the problem, the griddata documentation explains one possible way
that uses the natgrid algorithm.  A simpler solution that I often use is to
add a very small amount of noise to my regularly-spaced (x,y) points using
the numpy.random module.  I can give more details if you wish.

Ian

Hi,

Yannick Copin <yannick.copin@...> writes:
> Is it a bug in Qt4Agg, or an unimplemented feature? Is there any way 
> other than switching back to GTKAgg specifically?

just a follow-up and conclusion: I create a matplotlib issue for this
(https://github.com/matplotlib/matplotlib/issues/1646), and the use of
pyplot.pause in place of pyplot.draw seems to help.

Cheers,

Yannick

Hi,

I'm trying to contour some data that I have and the griddata line fails. I tried running it on some synthetically generated data and I get the same IndexError. Any Ideas?

Here is the example with the synthetic data:

x = y = arange(-10,10,0.01)

z = x**2+y**3

xi = yi = linspace(-10.1, 10.1, 100)

zi = griddata(x, y, z, xi, yi)
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-52-0458ab6ea672> in <module>()
----> 1 zi = griddata(x, y, z, xi, yi)

/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/site-packages/matplotlib/mlab.py in griddata(x, y, z, xi, yi, interp)
   2766             xi,yi = np.meshgrid(xi,yi)
   2767         # triangulate data
-> 2768         tri = delaunay.Triangulation(x,y)
   2769         # interpolate data
   2770         if interp == 'nn':

/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/site-packages/matplotlib/delaunay/triangulate.py in __init__(self, x, y)
     88             self.triangle_neighbors = delaunay(self.x, self.y)
     89 
---> 90         self.hull = self._compute_convex_hull()
     91 
     92     def _collapse_duplicate_points(self):

/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/site-packages/matplotlib/delaunay/triangulate.py in _compute_convex_hull(self)
    113 
    114         edges = {}
--> 115         edges.update(dict(zip(self.triangle_nodes[border[:,0]][:,1],
    116                               self.triangle_nodes[border[:,0]][:,2])))
    117         edges.update(dict(zip(self.triangle_nodes[border[:,1]][:,2],

IndexError: invalid index

Hi, All,

I am encountering a thorny problem when trying to run matplotlib under Windows 8.  If I label an axis using a command like

ax.set_ylabel(r'time (s)', name='Arial'),

all is well.  But if  try to add mathtext to that, as in

ax.set_ylabel(r'time ($s$)', name='Arial'),

mathtext.py throws an error (a very long stream) ending in "RuntimeError: Face has no glyph names".  If I remove the "name='Arial'" above and let the program default to Bitstream Vera Sans, the mathtext works.


This problem does not occur under Windows 7 or XP; only under two different Windows 8 installations.  Any ideas what's going on?

Chad