matplotlib-users Mailing List for matplotlib

Getting some strange artifacts when I save a figure as a PDF in 
matplotlib. Here are some screen shots. PDF <http://imgur.com/oQDXkWn> 
and PNG <http://imgur.com/bCw3Fn4>. Any idea why that is happening?
Here is (most of) the source code that makes the plot. I stripped out 
the data generation, because it is long and involved, and doesn't really 
matter. Basically what the script is supposed to do is make a scatter 
plot where the density is below some threshold, and a 2d histogram when 
it is above that threshold. The code seems to work fine, but when I save 
the figure (using savefig in Ipython) it shows up funny.
Thanks.
 import pylab as pyl
 bins = [50,50]
 thresh = 3
 xdat = #generate or load some data
 ydat = #generate or load some data
 hh, locx, locy = pyl.histogram2d(xdat, ydat, 
range=[[-1,4],[-26,-10]], bins=bins)
 posx = pyl.digitize(xdat, locx)
 posy = pyl.digitize(ydat, locy)
 # finds the bins which contain points. posx = 0 for points outside 
"range"
 ind = (posx > 0) & (posx <= bins[0]) & (posy > 0) & (posy <= bins[1])
 # values of histogram with points in the bins.
 hhsub = hh[posx[ind] - 1, posy[ind] - 1]
 xdat1 = xdat[ind][hhsub < thresh] # low density points
 ydat1 = ydat[ind][hhsub < thresh]
 hh[hh < thresh] = pyl.nan # fill the areas with low density by NaNs
 pyl.scatter(xdat1, ydat1, s=20, c='0.8')
 pyl.imshow(pyl.log10(hh.T), cmap='gray_r',
 extent=pyl.array([[-1,4],[-26,-10]]).flatten(), 
interpolation='none')
 pyl.show()
-- 
Steven Boada
Doctoral Student
Dept of Physics and Astronomy
Texas A&M University
bo...@ph...

The second example on
http://matplotlib.org/examples/pylab_examples/zorder_demo.html seems to
expose a bug, which is clearly visible in the vector version:
The blue curve with zorder=2 is plotted below the frame and all others with
zorder >= 3 are plotted above the frame. This is because the frame zorder is
hardcoded to be 2.5. This behaviour is certainly unexpected by most users.
How can one modify the mutual zorder of lines without conflicting with
standard axis elements?
--
View this message in context: http://matplotlib.1069221.n5.nabble.com/bug-in-zorder-example-tp45342.html
Sent from the matplotlib - users mailing list archive at Nabble.com.

INTRO
=====
please consider the following code (I'm trying to draw a timeline)
1 from matplotlib import pyplot, patches
2 fig = pyplot.figure()
3 ax = fig.add_subplot('111')
4 ax.add_patch(patches.Rectangle((1933,0.25), 73, 0.5))
5 pyplot.show()
that gives me a plot with the x axis that goes from 0.0 to 1.0,
now consider
 ...
5 ax.set_xlim((1933,1933+73))
6 pyplot.show()
this gives me an x axis that goes _exactly_ from 1933 to 2006,
eventually drawing a line superposed to the lower spine
 ...
5 ax.plot((1933,1933+73),(0,0))
6 pyplot.show()
gives me what I really want, that is an x axis running from 1930 to
2010, with the limits automatically rounded by matplotlib...
(I noted that the extra line forces a rounding also for the y axis
limits, but that's not a problem...)
QUESTION
========
I want matplotlib to round the limits of the x axis automatically,
when given explicitly the lower and upper limits of the data, how to?
Thank you in advance
-- 
"We have met the enemy and he is us."
 --- Pogo.