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I'm trying to extract all the vertices of hexagons that are returned from plt.hexbin. I then want to eventually convert them to shapely polygons, so I can use them with geopandas. At the moment I can only seem to extract one polygon from the PolyCollection returned by plt.hexbin

Does anybody have any advice as to how to return the full grid of hexbins?

This example will reproduce my problem,

import numpy as np
import geopandas as gpd
import matplotlib.pyplot as plt
from shapely.geometry import Point, Polygon
from matplotlib.patches import RegularPolygon


geoms = [Point(919.000, 533.500), Point(940.500, 528.500), 
 Point(937.000, 555.000), Point(889.000, 526.500), Point(898.000, 520.500)]

l = gpd.GeoDataFrame({'geometry':geoms})

y= np.array([ 533.500,  528.500,  555.000,  526.500,  520.500])
x= np.array([ 919.000,  940.500,  937.000,  889.000,  898.000])

f,ax=plt.subplots(1)
im =ax.hexbin(x,y, gridsize=(3,3), edgecolor='black')
l.plot(ax=ax, color='black', markersize=55)

Which produces this...

enter image description here

But when trying to extract the hexagons it produces a hexagon with the same position..

array_of_hexes=[]
for x,y in im.get_offsets():
    hexes = RegularPolygon((x, y), numVertices=6, radius= 5 )
    verts = hexes.get_path().vertices
    trans = im.get_transform()
    points = trans.transform(verts)
    array_of_hexes.append(Polygon(points))

gpd.GeoDataFrame({'geometry':array_of_hexes}).plot(edgecolor='black')

enter image description here

2

Incase anyone faces a similar issue, the resolution is:

collection = plt.hexbin(x,y, gridsize=(5,5)
hex_polys = collection.get_paths()[0].vertices
hex_array = []
for xs,ys in collection.get_offsets():
    hex_x = np.add(hex_polys[:,0],  xs)
    hex_y = np.add(hex_polys[:,1],  ys)
    hex_array.append(Polygon(np.vstack([hex_x, hex_y]).T))

hex_grid = gpd.GeoDataFrame({'geometry':hex_array})
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  • Thanks, this was very helpful! – Calvin Brown Feb 18 at 19:10

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