geopandas point in polygon

Question

I have a GeoDataFrame of polygons (~30) and a GeoDataFrame of Points (~10k)

I’m looking to create 30 new columns (with appropriate polygon names) in my GeoDataFrame of Points with a simple boolean True/False if the point is present in the polygon.

As an example, the GeoDataFrame of Polygons is this:

id  geometry
foo POLYGON ((-0.18353,51.51022, -0.18421,51.50767, -0.18253,51.50744, -0.1794,51.50914))
bar POLYGON ((-0.17003,51.50739, -0.16904,51.50604, -0.16488,51.50615, -0.1613,51.5091))

The GeoDataFrame of Points is like this:

counter     points
   1     ((-0.17987,51.50974))
   2     ((-0.16507,51.50925))

Expected output:

counter          points        foo    bar
   1    ((-0.17987,51.50974))  False  False
   1    ((-0.16507,51.50925))  False  False

I can do this manually by:

foo = df_poly.loc[df_poly.id=='foo']
df_points['foo'] = df_points['points'].map(lambda x: True if foo.contains(x).any()==True else False

But given that I have 30 polygons, I was wondering if there is a better way.
Appreciate any help!

Asked By: Kvothe

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Source

Answer 1

Not really clear what kind of data structures you actually have. Also, all your expected results are False, so that’s kind of hard to check. Assuming GeoSeries and GeoDataFrames, I would do this:

from shapely.geometry import Point, Polygon
import geopandas

polys = geopandas.GeoSeries({
    'foo': Polygon([(5, 5), (5, 13), (13, 13), (13, 5)]),
    'bar': Polygon([(10, 10), (10, 15), (15, 15), (15, 10)]),
})

_pnts = [Point(3, 3), Point(8, 8), Point(11, 11)]
pnts = geopandas.GeoDataFrame(geometry=_pnts, index=['A', 'B', 'C'])
pnts = pnts.assign(**{key: pnts.within(geom) for key, geom in polys.items()})

print(pnts)

And that gives me:

        geometry    bar    foo
A    POINT (3 3)  False  False
B    POINT (8 8)  False   True
C  POINT (11 11)   True   True

Answered By: Paul H

geopandas point in polygon

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