[Matplotlib-users] paths optimizer

[Al Niessner]

If I understand them both correctly (will need more time to fully
appreciate what the documentation is telling me) it seems I will need to
use both. I can use shapely to find the intersections in order to form
my new path and then use matplotlib patches to clip the original
polygons. Maybe shapely can clip too but I did not find it in the first
30 seconds that I was looking at the documentation.

Thanks for the help.

On Thu, 2015-11-12 at 08:21 +0000, Ian Thomas wrote:
> Hello Al,
> 
> The search terms you are looking for are 'polygon clipping' and
> 'boolean operations on polygons'.
> 
> 
> Matplotlib can clip one polygon with respect to another, there is a
> simple example at
> http://stackoverflow.com/questions/22612323/clipping-a-triagle-with-a-circle-in-matplotlib
> 
> 
> Alternatively, for more flexibility use shapely.  For example:
> 
>     from shapely.geometry import Polygon
>     a = Polygon([(0, 0), (1.1, 0), (1.1, 1.1), (0, 1.1)])
>     b = Polygon([(.9, 0), (2, 0), (2, 1.1), (.9, 1.1)])
>     c = Polygon([(.9, .9), (2, .9), (2, 2), (.9, 2)])
> 
>     d = a.intersection(b).intersection(c)
> 
>     print(d)
> 
> which outputs
> 
> POLYGON ((0.9 0.9, 0.9 1.1, 1.1 1.1, 1.1 0.9, 0.9 0.9))
> 
> i.e. a rectangle from x = 0.9 to 1.1 and y from 0.9 to 1.1.
> 
> 
> Ian Thomas
> 
> 
> 
> 
> On 12 November 2015 at 03:47, Al Niessner <Al.Niessner at gmx.net> wrote:
>         
>         I have three paths that each define a bounding box. Lets just
>         say I have
>         these three in (x,y) coordinates and all are moveto, lineto,
>         lineto,
>         lineto, and closepoly:
>         
>         1: (0, 0), (1.1, 0), (1.1, 1.1), (0, 1.1), (0, 0)
>         2: (.9, 0), (2, 0), (2, 1.1), (.9, 1.1), (.9, 0)
>         3: (.9, .9), (2, .9), (2, 2), (.9, 2) (.9, .9)
>         
>         While my paths have more nodes and are not as cleanly vertical
>         and
>         horizontal, it does cover the nature of what I am
>         experiencing.
>         
>         The first thing to note is that each box has overlap at x = 1
>         and y = 1
>         and all three boxes overlap at (1,1).
>         
>         What I am looking for is an optimizer that would be smart
>         enough to say
>         hey, because of the overlap, we can trim the boxes to:
>         
>         1: (0,0) (1,0) (1,1) (0,1) (0,0)
>         2: (1,0) (2,0) (2,1), (1,1), (1,0)
>         3: (1,1) (2,1) (2,2), (1,2), (1,1)
>         
>         I am not sure that optimizer is the right word to use either.
>         I have
>         poked around matplotlib a bit (over many years) and tried
>         searching but
>         guessing the search terms is not simple either. Hence, I am
>         asking if
>         anyone is aware of matplotlib functionality that will help me
>         do this
>         task. Any other tool outside of matplotlib would be just as
>         nice of a
>         suggestion. One last bit, it has to work for N paths.
>         
>         As always, thanks in advance.
>         
>         --
>         Al Niessner
>         
>         I have never found the companion that was so companionable as
>         solitude.
>         - From Walden by Henry David Thoreau
>         
>         The universe is indifferent, and life is brutal; however, it
>         is man's
>         choice of behavior that makes them malevolent rather than
>         benevolent.
>         
>         Some will fall in love with life and drink it from a fountain
>         That is pouring like an avalanche coming down the mountain.
>         - From the song Pepper by the Butthole Surfers
>         
>         
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>         Matplotlib-users at python.org
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> 
> 

-- 
Al Niessner

I have never found the companion that was so companionable as solitude.
- From Walden by Henry David Thoreau

The universe is indifferent, and life is brutal; however, it is man's
choice of behavior that makes them malevolent rather than benevolent.

Some will fall in love with life and drink it from a fountain
That is pouring like an avalanche coming down the mountain.
- From the song Pepper by the Butthole Surfers