matplotlib-users Mailing List for matplotlib

hi,
first, with backends agg and cairo, increasing the dpi increases the
width of any edge that is drawn, is there a way to set this edge width
constant?
second, when using backend_agg, if i draw a patch with an edge at x=0
and the xlim(xmin=0) there's still a 1 pixel gap.
this does not occur at the y-axis. and the gap does not occur with
backend_cairo. should i report this at the tracker?
a script to reproduce the error is below.
thanks,
-brent
from matplotlib.patches import Rectangle, Arrow
from matplotlib.figure import Figure
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
#from matplotlib.backends.backend_cairo import FigureCanvasCairo as FigureCanvas
alpha = 0
# NOTE: increasing the dpi increases the with of the edge.
dpi = 256
f = Figure(dpi=dpi)
c = FigureCanvas(f)
f.figurePatch.set_alpha(alpha)
f.ax = f.add_axes((0,0,1,1), alpha=alpha, frameon=False, xticks=() , yticks=())
px_width, px_height = 512, 512
f.set_size_inches(px_width/dpi, px_height/dpi)
f.ax.set_ylim(0, 10)
f.ax.set_xlim(0, 10)
f.ax.set_autoscale_on(False)
# NOTE: missing 1 pixel at x == 0
r = Rectangle((0, 0), 8, 8, fc='#ff0000')
f.ax.add_patch(r)
f.canvas.print_figure('k.png', dpi=dpi)

You need X11 based versions of Tcl/Tk and Python. I believe these are available 
through fink (or used to be), I build them from source. And then you can build 
matplotlib linking to these libraries (after tweaking setupext.py). It's 
somewhat involved but doable, actually you have to have a really good reason to 
do it. If you are still interested I can send you the gory details offline.
Nadia
Jeremy Hill wrote:
> Hello matplotlib-users,
> 
> I've just managed to get numpy, scipy, ipython and matplotlib running 
> under ActivePython 2.5 on my Intel Mac.
> 
> But I'd like matplotlib to use just X11, and not the Aqua-wrapped 
> thing with the rocket icon (app name "Python"): I want to be able to 
> ssh -X into my mac, run ipython in an xterm, and see matplotlib 
> figures in my X-window manager. At the moment, I've tried a few 
> different matplotlib backends, but for some (WX, WXAgg, Tk) 
> matplotlib pops up with its nice rocket icon on the physical screen 
> of my mac, even when I'm sshing in from elsewhere, whereas for others 
> (Agg, Agg2, Cairo), nothing pops up anywhere. Perhaps changing 
> backends is not the right approach, and I should be doing something 
> more fundamental...?
> 
> Apologies if I've missed something obvious---it's not a very 
> searchable problem. Googling and/or searching this list for "macos 
> x11 matplotlib" reveals that most people seem to want to go the other 
> way and eliminate their dependency on X11.
> 
> Below I've pasted an example of what I've been trying, followed by my 
> platform and installation info.
> 
> Thanks in advance for any pointers. cheers, --jez
> 
> 
> 
> 
> 
> 
> backend = 'Cairo'
> import matplotlib
> matplotlib.use(backend)
> import pylab,numpy
> pylab.plot(numpy.arange(0,10))
> pylab.show()
> 
> 
> Mac OS X 10.4.11 on 2.16 GHz Intel Core 2 Duo
> Python 2.5.2 (r252:60911, Mar 27 2008, 17:40:23)
> 	wget 'http://downloads.activestate.com/ActivePython/macosx/2.5/ 
> ActivePython-2.5.2.2-macosx.dmg'
> 	open ActivePython-2.5.2.2-macosx.dmg
> numpy.__version__ = '1.1.0.dev5038'
> 	svn co http://svn.scipy.org/svn/numpy/trunk numpy
> 	cd numpy
> 	python setup.py build
> 	sudo python setup.py install
> matplotlib.__version__ = '0.91.2'
> 	wget 'http://surfnet.dl.sourceforge.net/sourceforge/matplotlib/ 
> matplotlib-0.91.2.tar.gz'
> 	tar xfvz matplotlib-0.91.2.tar.gz
> 	cd matplotlib-0.91.2
> 	python setup.py build
> 	sudo python setup.py install
> cairo.version = '1.4.12'
> 	sudo port install cairo # installed cairo 1.4.14
> 	wget 'http://cairographics.org/releases/pycairo-1.4.12.tar.gz'
> 	tar xfvz pycairo-1.4.12.tar.gz
> 	cd pycairo-1.4.12
> 	./configure --prefix=`python -c "import sys; print sys.prefix"`
> 	make
> 	sudo make install
> 
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Hello matplotlib-users,
I've just managed to get numpy, scipy, ipython and matplotlib running 
under ActivePython 2.5 on my Intel Mac.
But I'd like matplotlib to use just X11, and not the Aqua-wrapped 
thing with the rocket icon (app name "Python"): I want to be able to 
ssh -X into my mac, run ipython in an xterm, and see matplotlib 
figures in my X-window manager. At the moment, I've tried a few 
different matplotlib backends, but for some (WX, WXAgg, Tk) 
matplotlib pops up with its nice rocket icon on the physical screen 
of my mac, even when I'm sshing in from elsewhere, whereas for others 
(Agg, Agg2, Cairo), nothing pops up anywhere. Perhaps changing 
backends is not the right approach, and I should be doing something 
more fundamental...?
Apologies if I've missed something obvious---it's not a very 
searchable problem. Googling and/or searching this list for "macos 
x11 matplotlib" reveals that most people seem to want to go the other 
way and eliminate their dependency on X11.
Below I've pasted an example of what I've been trying, followed by my 
platform and installation info.
Thanks in advance for any pointers. cheers, --jez
backend = 'Cairo'
import matplotlib
matplotlib.use(backend)
import pylab,numpy
pylab.plot(numpy.arange(0,10))
pylab.show()
Mac OS X 10.4.11 on 2.16 GHz Intel Core 2 Duo
Python 2.5.2 (r252:60911, Mar 27 2008, 17:40:23)
	wget 'http://downloads.activestate.com/ActivePython/macosx/2.5/ 
ActivePython-2.5.2.2-macosx.dmg'
	open ActivePython-2.5.2.2-macosx.dmg
numpy.__version__ = '1.1.0.dev5038'
	svn co http://svn.scipy.org/svn/numpy/trunk numpy
	cd numpy
	python setup.py build
	sudo python setup.py install
matplotlib.__version__ = '0.91.2'
	wget 'http://surfnet.dl.sourceforge.net/sourceforge/matplotlib/ 
matplotlib-0.91.2.tar.gz'
	tar xfvz matplotlib-0.91.2.tar.gz
	cd matplotlib-0.91.2
	python setup.py build
	sudo python setup.py install
cairo.version = '1.4.12'
	sudo port install cairo # installed cairo 1.4.14
	wget 'http://cairographics.org/releases/pycairo-1.4.12.tar.gz'
	tar xfvz pycairo-1.4.12.tar.gz
	cd pycairo-1.4.12
	./configure --prefix=`python -c "import sys; print sys.prefix"`
	make
	sudo make install

John Burkhart wrote:
> Dear Jeffrey Whitaker,
> 
> I've been working with and using matplotlib and your basemap toolbox. 
> Terrific work! It's a lot of fun to use. I'm currently aboard the R/V 
> Knorr and have no internet - only email - hence my correspondence to you 
> directly rather than via a forum.
> 
> I've now used your warpimage.py example to transform and create a 
> basemap from a cylindrically projected image, but now I want to use one 
> which is polar stereographic. Unfortunately, I cannot include 
> attachments, but basically, I'm trying to overly images on this file:
> http//:polarview.met.no/highres/sarmap2.jpg and another (c_map1.jpg)
> 
> How do I go the other way? That is, to use m.transform_scalar to convert 
> a polar stereographic image to another projection?
> 
> Thanks so much.
> 
> Via InMarsat,
> john
> 
> Here is the geotiff information for the c_map1.jpg file:
> Driver: GTiff/GeoTIFF
> Files: ice20080416.tif
> Size is 4149, 3150
> Coordinate System is:
> PROJCS["unnamed",
> GEOGCS["WGS 84",
> DATUM["WGS_1984",
> SPHEROID["WGS 84",6378137,298.2572235629972,
> AUTHORITY["EPSG","7030"]],
> AUTHORITY["EPSG","6326"]],
> PRIMEM["Greenwich",0],
> UNIT["degree",0.0174532925199433],
> AUTHORITY["EPSG","4326"]],
> PROJECTION["Polar_Stereographic"],
> PARAMETER["latitude_of_origin",90],
> PARAMETER["central_meridian",0],
> PARAMETER["scale_factor",1],
> PARAMETER["false_easting",0],
> PARAMETER["false_northing",0],
> UNIT["metre",1,
> AUTHORITY["EPSG","9001"]]]
> Origin = (-1700500.241080038715154,-149240.597878495842451)
> Pixel Size = (1000.482160077145636,-1000.482160077145522)
> Metadata:
> AREA_OR_POINT=Area
> Image Structure Metadata:
> INTERLEAVE=PIXEL
> Corner Coordinates:
> Upper Left (-1700500.241, -149240.598) ( 84d59'3.89"W, 74d48'10.68"N)
> Lower Left (-1700500.241,-3300759.402) ( 27d15'24.57"W, 57d36'46.68"N)
> Upper Right ( 2450500.241, -149240.598) ( 86d30'53.54"E, 68d16'24.80"N)
> Lower Right ( 2450500.241,-3300759.402) ( 36d35'25.36"E, 54d20'41.99"N)
> Center ( 375000.000,-1725000.000) ( 12d15'53.19"E, 74d17'25.72"N)
> Band 1 Block=4149x1 Type=Byte, ColorInterp=Red
> Band 2 Block=4149x1 Type=Byte, ColorInterp=Green
> Band 3 Block=4149x1 Type=Byte, ColorInterp=Blue
>
Hi John:
If your image had no borders of annotations, you could read it in and 
get the RGB values of each pixel using PIL (following the example in 
warpimage.py). You could then
1) compute the polar stereographic coordinates of the rectilinear grid 
you want to interpolate to
2) use the interp function to interpolate the RGB values from the 
original polar stereographic grid to the new grid.
Here's part of the docstring for the interp function:
def interp(datain,xin,yin,xout,yout,checkbounds=False,masked=False,order=1):
 """
 dataout = interp(datain,xin,yin,xout,yout,order=1)
 interpolate data (datain) on a rectilinear grid (with x=xin
 y=yin) to a grid with x=xout, y=yout.
 datain is a rank-2 array with 1st dimension corresponding to y,
 2nd dimension x.
 xin, yin are rank-1 arrays containing x and y of
 datain grid in increasing order.
 xout, yout are rank-2 arrays containing x and y of desired output 
grid."""
Here xin and yin would be the (1d) polar stereographic coords of the 
original image grid. xout, yout would be the (2d) coordinates of the 
new grid (in the same polar stereographic coordinates as the original 
image grid, even though the new grid is a different map projection).
You can use the Basemap instances defined for each projection to compute 
the coordinates of each grid, and to transform the new grid into the 
projection coordinates of the original grid.
It's tricky, but should be possible if the image doesn't have any 
whitespace or annotations around the edges. Unfortunately, the image 
you point to doesn't appear to be that simple.
I'm copying the matplotlib-users list just in case anyone has a better 
suggestion ...
-Jeff
-- 
Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/PSD R/PSD1 Email : Jef...@no...
325 Broadway Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg

Paul Smith wrote:
> Hi,
> I can't find a way to plot marker symbols that have a transparent face colour, 
> so I can see the contour plot that's under them. Setting alpha affects the 
> edge colour as well.
> Any suggestions?
Paul,
If you want the symbol faces to be completely transparent, set 
mfc='None' (with quotes):
plot([1,2,3], 'o', mfc='None')
If you need them to be colored but with an alpha, then you will have to 
plot twice, once for the edges as above (adding an alpha kwarg if 
desired), and the second time for the centers with markeredgewidth=0 to 
turn off the edges. (For consistency one might expect mec='None' should 
work the same way, but it doesn't.)
The drawing model is such that alpha is attached to the whole marker, 
and can't be set separately for edge and face without making two 
separate markers, as suggested above. Note also that postscript doesn't 
support alpha at all.
Eric
> Paul
> 
> 
> -------------------------------------------------------------------------
> This SF.net email is sponsored by the 2008 JavaOne(SM) Conference 
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> _______________________________________________
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Hi everybody,
Is there a function in matplotlib for hexagonal binning of scatter plots? Here are some examples of what I am looking for:
http://faculty.washington.edu/tlumley/survey/greyhexbin.png
http://www.spss.com/research/wilkinson/nViZn/hexbin.gif
http://addictedtor.free.fr/graphiques/75x75/tn_139.png
Thanks!
--Michiel.
 between 0000-00-00 and 9999-99-99 

Hi,
I can't find a way to plot marker symbols that have a transparent face colour, 
so I can see the contour plot that's under them. Setting alpha affects the 
edge colour as well.
Any suggestions?
Paul