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PS backend fails to savefig() pcolormesh with gouraud shading #1993

Merged
merged 1 commit into from May 16, 2013
Merged

PS backend fails to savefig() pcolormesh with gouraud shading #1993

merged 1 commit into from May 16, 2013

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mdboom
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@mdboom mdboom commented May 16, 2013

Following script

import numpy as np
from matplotlib.pyplot import figure, savefig

n = 12
x = np.linspace(-1.5,1.5,n)
y = np.linspace(-1.5,1.5,n*2)
X,Y = np.meshgrid(x,y);

Qx = np.cos(Y) - np.cos(X)
Qz = np.sin(Y) + np.sin(X)
Qx = (Qx + 1.1)
Z = np.sqrt(X**2 + Y**2)/5;
Z = (Z - Z.min()) / (Z.max() - Z.min())

fig = figure()
ax = fig.add_subplot(111)
ax.pcolormesh(Qx,Qz,Z, shading='gouraud')
savefig('bug.eps')

results in

Traceback (most recent call last):
  File "quad.py", line 20, in <module>
    savefig('bug.eps')
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/pyplot.py", line 494, in savefig
    return fig.savefig(*args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/figure.py", line 1403, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_qt4agg.py", line 161, in print_figure
    FigureCanvasAgg.print_figure(self, *args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backend_bases.py", line 2158, in print_figure
    **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backend_bases.py", line 1886, in print_eps
    return ps.print_eps(*args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 974, in print_eps
    return self._print_ps(outfile, 'eps', *args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 1002, in _print_ps
    **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 1095, in _print_figure
    self.figure.draw(renderer)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/figure.py", line 1027, in draw
    func(*args)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/axes.py", line 2086, in draw
    a.draw(renderer)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/artist.py", line 54, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/collections.py", line 1745, in draw
    gc, triangles, colors, transform.frozen())
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 827, in draw_gouraud_triangles
    points = trans.transform(points)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/transforms.py", line 1561, in transform
    return self.transform_affine(values)
  File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/transforms.py", line 1645, in transform_affine
    return affine_transform(points, mtx)
ValueError: Invalid vertices array.

Tested with

commit af07100823d219e51f061cfc8e96d957fa661126

BUILDING MATPLOTLIB
            matplotlib: yes [1.3.x]
                python: yes [2.7.4 (default, Apr 21 2013, 14:51:13)  [GCC
                        4.7.2]]
              platform: yes [linux2]

REQUIRED DEPENDENCIES AND EXTENSIONS
                 numpy: yes [version 1.6.2]
              dateutil: yes [using dateutil version 2.1]
               tornado: yes [using tornado version 2.3]
             pyparsing: yes [using pyparsing version 1.5.7]
                 pycxx: yes [pkg-config information for 'PyCXX' could not be
                        found. Using local copy.]
                libagg: yes [pkg-config information for 'libagg' could not
                        be found. Using local copy.]
              freetype: yes [version 16.0.10]
                   png: yes [version 1.6.1]

OPTIONAL SUBPACKAGES
           sample_data: yes [installing]
              toolkits: yes [installing]
                 tests: yes [using nose version 1.1.2]

OPTIONAL BACKEND EXTENSIONS
                macosx: no  [Mac OS-X only]
                qt4agg: yes [Qt: 4.8.2, PyQt4: 4.9.2]
               gtk3agg: yes [version 3.3.6]
             gtk3cairo: yes [version 3.3.6]
                gtkagg: yes [Gtk: 2.24.17 pygtk: 2.24.0]
                 tkagg: yes [version 81008]
                 wxagg: yes [version 2.8.12.1]
                   gtk: yes [Gtk: 2.24.17 pygtk: 2.24.0]
                 qtagg: no  [pyqt not found]
                   agg: yes [installing]
                 cairo: yes [version 1.10.0]

OPTIONAL LATEX DEPENDENCIES
                dvipng: yes [version Larsson]
           ghostscript: yes [version 9.06]
                 latex: yes [version 3.1415926]
               pdftops: yes [version 0.22.3]

@mdboom
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mdboom commented May 11, 2013

Unfortunately, since PS doesn't support alpha transparency, gouraud shading
isn't possible. In any event, we should definitely improve this error
message.
On May 11, 2013 8:15 AM, "Kacper Kowalik" notifications@github.com wrote:

Following script

import numpy as npfrom matplotlib.pyplot import figure, savefig
n = 12x = np.linspace(-1.5,1.5,n)y = np.linspace(-1.5,1.5,n_2)X,Y = np.meshgrid(x,y);
Qx = np.cos(Y) - np.cos(X)Qz = np.sin(Y) + np.sin(X)Qx = (Qx + 1.1)Z = np.sqrt(X__2 + Y_*2)/5;Z = (Z - Z.min()) / (Z.max() - Z.min())
fig = figure()ax = fig.add_subplot(111)ax.pcolormesh(Qx,Qz,Z, shading='gouraud')savefig('bug.eps')

results in

Traceback (most recent call last):
File "quad.py", line 20, in
savefig('bug.eps')
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/pyplot.py", line 494, in savefig
return fig.savefig(_args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/figure.py", line 1403, in savefig
self.canvas.print_figure(_args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_qt4agg.py", line 161, in print_figure
FigureCanvasAgg.print_figure(self, _args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backend_bases.py", line 2158, in print_figure
*_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backend_bases.py", line 1886, in print_eps
return ps.print_eps(_args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 974, in print_eps
return self._print_ps(outfile, 'eps', *args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 1002, in _print_ps
*_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 1095, in _print_figure
self.figure.draw(renderer)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/artist.py", line 54, in draw_wrapper
draw(artist, renderer, *args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/figure.py", line 1027, in draw
func(_args)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/artist.py", line 54, in draw_wrapper
draw(artist, renderer, *args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/axes.py", line 2086, in draw
a.draw(renderer)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/artist.py", line 54, in draw_wrapper
draw(artist, renderer, _args, *_kwargs)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/collections.py", line 1745, in draw
gc, triangles, colors, transform.frozen())
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/backends/backend_ps.py", line 827, in draw_gouraud_triangles
points = trans.transform(points)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/transforms.py", line 1561, in transform
return self.transform_affine(values)
File "/tmp/matplotlib/build/lib.linux-x86_64-2.7/matplotlib/transforms.py", line 1645, in transform_affine
return affine_transform(points, mtx)
ValueError: Invalid vertices array.

Tested with

commit af07100

BUILDING MATPLOTLIB
matplotlib: yes [1.3.x]
python: yes [2.7.4 (default, Apr 21 2013, 14:51:13) [GCC
4.7.2]]
platform: yes [linux2]

REQUIRED DEPENDENCIES AND EXTENSIONS
numpy: yes [version 1.6.2]
dateutil: yes [using dateutil version 2.1]
tornado: yes [using tornado version 2.3]
pyparsing: yes [using pyparsing version 1.5.7]
pycxx: yes [pkg-config information for 'PyCXX' could not be
found. Using local copy.]
libagg: yes [pkg-config information for 'libagg' could not
be found. Using local copy.]
freetype: yes [version 16.0.10]
png: yes [version 1.6.1]

OPTIONAL SUBPACKAGES
sample_data: yes [installing]
toolkits: yes [installing]
tests: yes [using nose version 1.1.2]

OPTIONAL BACKEND EXTENSIONS
macosx: no [Mac OS-X only]
qt4agg: yes [Qt: 4.8.2, PyQt4: 4.9.2]
gtk3agg: yes [version 3.3.6]
gtk3cairo: yes [version 3.3.6]
gtkagg: yes [Gtk: 2.24.17 pygtk: 2.24.0]
tkagg: yes [version 81008]
wxagg: yes [version 2.8.12.1]
gtk: yes [Gtk: 2.24.17 pygtk: 2.24.0]
qtagg: no [pyqt not found]
agg: yes [installing]
cairo: yes [version 1.10.0]

OPTIONAL LATEX DEPENDENCIES
dvipng: yes [version Larsson]
ghostscript: yes [version 9.06]
latex: yes [version 3.1415926]
pdftops: yes [version 0.22.3]

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/1993
.

@mdboom
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mdboom commented May 16, 2013

My bad -- I was obviously out to lunch when I said PS doesn't support Gouraud shading. PS Level 3 has explicit support for it.

The attached patch (I believe) addresses the issue. Can you confirm?

@Xarthisius
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Works like a charm! Just in time for drop-in replacement for a figure in my paper ;-) Thank you very much!

mdboom added a commit that referenced this pull request May 16, 2013
@mdboom
Merge pull request #1993 from mdboom/ps-gouraud
accd49c 
PS backend fails to savefig() pcolormesh with gouraud shading
@mdboom mdboom merged commit accd49c into matplotlib:v1.2.x May 16, 2013
@mdboom mdboom deleted the ps-gouraud branch August 7, 2014 13:49
@anntzer anntzer mentioned this pull request Jan 14, 2020
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