pylab.imshow() does not handle clip_path properly

This is a bug report for matplotlib version 0.99.1.1

The clip_path keyword of imshow() does not work when setting it to (Path, Transform) for two reasons:

1. On line 622 of artist.py, v is now the tuple (Path,Transform) and should be apply to func with apply(func,v). Hence the following suggested change:

          for k,v in props.items():
              func = getattr(self, 'set_'+k, None)
              if func is None or not callable(func):
                  raise AttributeError('Unknown property %s'%k)
< func(v)
> if type(v) is tuple:
> apply(func,v)
              else:
                  func(v)
              changed = True

2. On line 6278 of axes.py, im.set_clip_path(self.patch) should not overwrite the clip path if already set. Hence the following suggested change:

          im.set_data(X)
          im.set_alpha(alpha)
          self._set_artist_props(im)
< im.set_clip_path(self.patch)
> if not im._clipon:
> im.set_clip_path(self.patch)
          #if norm is None and shape is None:
          # im.set_clim(vmin, vmax)
          if vmin is not None or vmax is not None:
              im.set_clim(vmin, vmax)
          else:
              im.autoscale_None()
          im.set_url(url)

Gellule Xg wrote:

This is a bug report for matplotlib version 0.99.1.1

The clip_path keyword of imshow() does not work when setting it to
(Path, Transform) for two reasons:

Hi, Thanks for the report. Do you have a simple test script that we can
use to see the problem and then fix it? We will then use this as the
basis to create a test function to make sure the issue never "crops" up
again.

-Andrew

Gellule Xg wrote:

This is a bug report for matplotlib version 0.99.1.1

The clip_path keyword of imshow() does not work when setting it to (Path, Transform) for two reasons:

1. On line 622 of artist.py, v is now the tuple (Path,Transform) and should be apply to func with apply(func,v). Hence the following suggested change:

          for k,v in props.items():
              func = getattr(self, 'set_'+k, None)
              if func is None or not callable(func):
                  raise AttributeError('Unknown property %s'%k)
< func(v)
> if type(v) is tuple:
> apply(func,v)
              else:
                  func(v)

apply is deprecated. The block above could be written in one line as

                 func(*tuple(v))

Eric

···

              changed = True

2. On line 6278 of axes.py, im.set_clip_path(self.patch) should not overwrite the clip path if already set. Hence the following suggested change:

          im.set_data(X)
          im.set_alpha(alpha)
          self._set_artist_props(im)
< im.set_clip_path(self.patch)
> if not im._clipon:
> im.set_clip_path(self.patch)
          #if norm is None and shape is None:
          # im.set_clim(vmin, vmax)
          if vmin is not None or vmax is not None:
              im.set_clim(vmin, vmax)
          else:
              im.autoscale_None()
          im.set_url(url)

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This is a bug report for matplotlib version 0.99.1.1

The clip_path keyword of imshow() does not work when setting it to (Path, Transform) for two reasons:

Hi, Thanks for the report. Do you have a simple test script that we can
use to see the problem and then fix it? We will then use this as the
basis to create a test function to make sure the issue never "crops" up
again.

-Andrew

Hi Andrew,
Please try the following. It's a script that clips an NxN image based on its contour.
Thanks,
-Julien

import numpy
import pylab

#Create a NxN image
N=100
(x,y) = numpy.indices((N,N))
x -= N/2
y -= N/2
r = numpy.sqrt(x**2+y**2-x*y)

#Create a contour plot at N/4 and extract both the clip path and transform
c=pylab.contour(r,[N/4])
clipPath = c.collections[0].get_paths()[0]
clipTransform = c.collections[0].get_transform()

#Plot the image clipped by the contour
pylab.imshow(r, clip_path=(clipPath,clipTransform))
pylab.show()

Gellule Xg wrote:

This is a bug report for matplotlib version 0.99.1.1

The clip_path keyword of imshow() does not work when setting it to (Path, Transform) for two reasons:
      

Hi, Thanks for the report. Do you have a simple test script that we can
use to see the problem and then fix it? We will then use this as the
basis to create a test function to make sure the issue never "crops" up
again.

-Andrew
    
Hi Andrew,
Please try the following. It's a script that clips an NxN image based on its contour.
Thanks,
-Julien
  

Hi Julien,

I made a couple fixes to MPL 0.99 maintenance branch and then added a modified version your example in the tests. See http://matplotlib.svn.sourceforge.net/viewvc/matplotlib/trunk/matplotlib/lib/matplotlib/tests/test_axes.py?r1=7870&r2=7869&pathrev=7870

You should be able to use this approach to do what you were originally after.

My actual fixes to MPL were in r7866 and r7867. I had to take a slightly different approach than your suggestion. The approach I implemented based on your initial patch doesn't access private variables or change the way calling setters methods works.

-Andrew