[matplotlib-devel] bug in imshow for PDF, EPS output
Hi all,
I've come across an apparent bug in imshow when outputting to PDF and
EPS files. (I haven't tested other vector formats.) It manifests as
a small scaling error between the raster image and the axes coordinates.
I have attached a test script to illustrate the problem. The
(correct) PNG output file shows a green 'X' at the common point
between four pixels near the center of the raster image. The extent
is chosen such that the coordinates refer to pixel centers. The PDF
and EPS output files show a misalignment between the X and the pixel
boundaries -- zoom in to see it clearly. Also, the topmost row and
rightmost column appear truncated.
I am using svn r7395.
Thanks for the attention,
Mike
import numpy as n
import matplotlib as mpl
import pylab
ny, nx = 50, 50
im = n.arange(ny*nx) % 3
im.shape = (ny, nx)
extent = (-0.5, nx-0.5, -0.5, ny-0.5)
fig = pylab.figure(0, figsize=(5,5))
fig.clear()
fig.hold(True)
ax = fig.add_subplot(111)
ax.imshow(im, extent=extent,
interpolation='nearest',
cmap=mpl.cm.gray,
origin='lower')
ax.set_autoscale_on(False)
ax.plot(((nx-1)/2.,), ((ny-1)/2.,), 'x', c='g', ms=4, mew=1.25)
pylab.draw()
#pylab.show()
dpi = 300
pylab.savefig('test.png', dpi=dpi)
pylab.savefig('test.pdf', dpi=dpi)
pylab.savefig('test.eps', dpi=dpi)
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[matplotlib-devel] LineCollection and alpha
Hi all,
I found a small bug in LineCollection, which gives an exception when setting
alpha. This is manifested in e.g. hlines and vlines:
In [1]: hlines((0,),(-1,),(1,),color='b',alpha=0.1)
---
IndexErrorTraceback (most recent call last)
XXX/ipython console in module()
XXX/lib/python/matplotlib/pyplot.py in hlines(*args, **kwargs)
1700 hold(h)
1701 try:
- 1702 ret = gca().hlines(*args, **kwargs)
1703 draw_if_interactive()
1704 except:
XXX/lib/python/matplotlib/axes.py in hlines(self, y, xmin, xmax, colors,
linestyles, label, **kwargs)
2609 linestyles=linestyles,
label=label)
2610 self.add_collection(coll)
- 2611 coll.update(kwargs)
2612
2613 minx = min(xmin.min(), xmax.min())
XXX/lib/python/matplotlib/artist.py in update(self, props)
438 if func is None or not callable(func):
439 raise AttributeError('Unknown property %s'%k)
-- 440 func(v)
441 changed = True
442 self.eventson = store
XXX/lib/python/matplotlib/collections.py in set_alpha(self, alpha)
306 else:
307 artist.Artist.set_alpha(self, alpha)
-- 308 self._facecolors[:, 3] = alpha
309 self._edgecolors[:, 3] = alpha
310
IndexError: invalid index
This appears to be because LineCollection.__init__() only uses
Collection._edgecolors, and sets _facecolors to an empty array. I don't
know if it's the proper solution, but I did this to get it to work:
Index: lib/matplotlib/collections.py
===
--- lib/matplotlib/collections.py (revision 5000)
+++ lib/matplotlib/collections.py (working copy)
@@ -305,7 +305,8 @@
except TypeError: raise TypeError('alpha must be a float')
else:
artist.Artist.set_alpha(self, alpha)
-self._facecolors[:, 3] = alpha
+if len(self._facecolors):
+self._facecolors[:, 3] = alpha
self._edgecolors[:, 3] = alpha
def get_linewidths(self):
Best,
Mike
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[matplotlib-devel] Arrow bugfix
Hi all, I encountered problems with the Arrow patch, which broke sometime recently. I'm attaching a fix (diff against svn r4999). Best, Mike arrow_patch.diff Description: Binary data - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
[matplotlib-devel] small bugfix
Hi all, I found a small bug, where Figure.clf() was erroneously leaving some axes instances in the Figure.axes list. It turns out the method was deleting items from the list while iterating over it. Attached is a patch. Mike Index: figure.py === --- figure.py (revision 3198) +++ figure.py (working copy) @@ -1,7 +1,7 @@ Figure class -- add docstring here! -import sys +import sys, copy import artist from artist import Artist from axes import Axes, Subplot, PolarSubplot, PolarAxes @@ -515,7 +515,7 @@ Clear the figure -for ax in self.axes: +for ax in copy.copy(self.axes): ax.cla() self.delaxes(ax) - Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.phpp=sourceforgeCID=DEVDEV___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
[matplotlib-devel] PS, dpi, and imshow
Hi all, I have a question about the PS backend (building on the thread imshow with PS backend from ~ a month ago). Evidently this backend is fixed at 72 dpi. This isn't a problem with vector information. However, it would seem that one would want to use a higher resolution when plotting figures that use imshow() for raster data, since this command has several choices for interpolation. As I understand, the AxesImage is sampled at this low-resolution when being written to PS/ EPS. Subsequent interpolation is done when printing, or viewing with ghostview. For the (originally?) raster data, gv seems to use a nearest-neighbor scheme, making the image blocky. It would be nice to use matplotlib's interpolation instead. Is there a fundamental reason this needs to be fixed at 72 dpi? As some publishers ask for EPS files of e.g. 300 dpi, I would think it's theoretically possible to export at different resolutions. My understanding is that the _preview_ image in the file is supposed to be 72 dpi. One possible workaround is to scale up the size of the figure (in inches), but then fonts, line thickness, marker sizes, etc. must also be scaled, making it less-than-satisfactory. Thank you in advance for any enlightenment, and please forgive my ignorance -- I must admit I don't know that much about PS, nor about the specific scheme used in matplotlib for getting the image data into the postscript file, so I may be critically mistaken in the above assessment. Best, Mike (P.S. please cc me, as I'm not subscribed) - Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnkkid=120709bid=263057dat=121642 ___ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
