Why not just use boolean indexing?
E.g. to find the region that falls between 5 and 10, do "(z >=5) & (z <=
10)":
In [1]: import numpy as np
In [2]: x, y = np.mgrid[-10:10, -10:10]
In [3]: z = np.hypot(x, y)
In [4]: result = (z >= 5) & (z <= 10)
In [5]: result.astype(int)
Out[5]:
array([[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
[0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1],
[1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1],
[0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1],
[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
[0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0],
[0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0]])
Cheers,
-Joe
On Thu, Aug 28, 2014 at 8:23 PM, Eric Firing <efir...@hawaii.edu> wrote:
> On 2014/08/28, 3:02 AM, Matthew Czesarski wrote:
> > Hi Matplotlib Users!
> >
> >
> >
> > I have some 2-d arrays, which i am displaying with implot, and deriving
> > contours for with contour. Easy - I'm just pulling them out of
> > collections[0].get_paths() .
> >
> > However what's not easy is that I would like to recover a 1-0 or
> > True-False array of the array values (pixels) that fall within the
> > contours. Some line crossing algorithm/floodfill could do it, but I
> > guess that matplotlib's fill() or contourf() must do this under the hood
> > anyway. I've looked into the output both functions, but I don't see
> > anything obvious..
> >
> > Does anybody know if there's an a way to pull out a such an array from
> > matplotlib? Any pointers are appreciated!
>
> Make an array of (x, y) pairs from the X and Y you use in your call to
> contour, and then feed that array to the contains_points() method of
> your contour Path. This will give you the desired Boolean array for any
> given Path; depending on what you want, you might need to combine arrays
> for more than one Path.
>
> To get closed paths, I think you will want to use contourf, not contour.
>
> Eric
>
>
>
> >
> > Cheers,
> > Matt
> >
> >
> >
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