CODEWITHSUNDEEP
pythonpython-3.xpandas
tom91
tom91

Reputation: 685

Adding True or False to a new column based on for loop

I have a list of named polygons:

import pandas as pd
import geopandas as gp
df = gp.GeoDataFrame([['a',Polygon([(1, 0), (1, 1), (2,2), (1,2)])],
                     ['b',Polygon([(1, 1), (2,2), (3,1)])]],
                     columns = ['name','geometry'])
df = gp.GeoDataFrame(df, geometry = 'geometry')

and a list of named points:

points = gp.GeoDataFrame( [['box', Point(1.5, 1.75)],
                          ['cone', Point(3.0,2.0)],
                        ['triangle', Point(2.5,1.25)]],
                     columns=['id', 'geometry'], 
                     geometry='geometry')

Currently, I am running a for loop over these points and polygons to see which point falls within which polygon and returning there names and Ids to a list loc like so:

loc = []

for geo1, name in zip(df['geometry'], df['name']):
    for geo2, id in zip(points['geometry'], points['id']):
        if geo1.contains(geo2):
            loc.append([id, name])

Now what I want to try and do is alter the loop so it adds a column to the points dataframe called 'inside' and returns 'True' if the point is in a polygon and 'False' if it isn't.

I've tried:

points['inside'] = ''
for geo1 in df['geometry']:
    for geo2 in points['geometry']:
        if geo1.contains(geo2):
            points['inside'].append('True')

but it doesn't work

How can I best do this?

sorry if there is a very basic answer that I have missed.

Its been suggested below that this might be a duplicate of another question, however the one that is linked does not refer to adding the results to a column and whilst the Matplotlib methodology may be faster, when I run the example script provided I get the error float() argument must be a string or a number, not 'zip'

Upvotes: 1

Views: 273

Answers (1)

Moshe Slavin
Moshe Slavin

Reputation: 5204

You are trying to append to a string...

Just change the line points['inside'] = '' to points['inside'] = []

points['inside'] = []
for geo1 in df['geometry']:
    for geo2 in points['geometry']:
        if geo1.contains(geo2):
            points['inside'].append('True')

This works for me...

Hope you find this helpful!

Upvotes: 1

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