Clipping

Community matplotlib-users
1

All,

I'm looking at:

http://matplotlib.sourceforge.net/examples/api/clippath_demo.html

But I cannot figure out:

patch=patches.Circle((300, 300), radius=100)

Where precisely is (300,300)?

D.

2

I believe it's in window coordinates (pixels), with 0,0 being the lower left.

Ryan

···

On Wed, Feb 17, 2010 at 6:44 PM, David Arnold <dwarnold45@...2108...> wrote:

All,

I'm looking at:

http://matplotlib.sourceforge.net/examples/api/clippath_demo.html

But I cannot figure out:

patch=patches.Circle((300, 300), radius=100)

Where precisely is (300,300)?

--
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma

3

The coordinates for Circle (and all patches) are in data coordinates. So the (300, 300) is relative to the values in the data itself. When adding a patch directly to a plot, however, the limits may not automatically update, so you may need to call axes.set_xlim or axes.set_ylim to adjust them to make the circle visible.

Mike

Ryan May wrote:

···

On Wed, Feb 17, 2010 at 6:44 PM, David Arnold <dwarnold45@...2108...> wrote:
  

All,

I'm looking at:

http://matplotlib.sourceforge.net/examples/api/clippath_demo.html

But I cannot figure out:

patch=patches.Circle((300, 300), radius=100)

Where precisely is (300,300)?
    
I believe it's in window coordinates (pixels), with 0,0 being the lower left.

Ryan

--
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA

4

In this example, though, he is not adding the Circle to the Axes via
add_patch (so the transData transform is not set).

Rather, he is using it to set the clip path

  http://matplotlib.sourceforge.net/examples/api/clippath_demo.html

So I think Ryan's answer is correct.

But David, if you want the clippath to be in data coordinates, you can
set the transform yourself

  patch = patches.Circle((300,300), radius=100, transform=ax.transData)

See the transformations tutorial for more about the coordinate systems
and transformations

  http://matplotlib.sourceforge.net/users/transforms_tutorial.html

JDH

···

On Mon, Feb 22, 2010 at 10:11 AM, Michael Droettboom <mdroe@...86...> wrote:

The coordinates for Circle (and all patches) are in data coordinates.
So the (300, 300) is relative to the values in the data itself. When
adding a patch directly to a plot, however, the limits may not
automatically update, so you may need to call axes.set_xlim or
axes.set_ylim to adjust them to make the circle visible.