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I have a network formed with two Polygons and I want to now which nodes are only in the bigger Polygon. How can I do this?

Here is the code:

import osmnx as ox
import igraph as ig
import matplotlib.pyplot as plt
import pandas as pd
import networkx as nx

city = ['Portugal, Lisbon', 'Portugal, Amadora']
G = ox.graph_from_place(city, network_type='drive', simplify=True)
G_nx = nx.relabel.convert_node_labels_to_integers(G)
nodes, edges = ox.graph_to_gdfs(G_nx, nodes=True, edges=True)

Here are the Polygons: enter image description here

The smaller Polygon is Amadora and the other Lisbon

DPM
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1 Answers1

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You are looking for a within spatial operation. Such an operation is elementary in spatial analysis, and as such, I would encourage you to carefully read the documentation of the tools you are using to understand their underlying concepts and usage. If working with OSMnx, this would include networkx (for network analysis) and geopandas (for spatial analysis). For example, the within method is described in detail and given usage examples in the geopandas documentation.

import osmnx as ox
ox.config(use_cache=True, log_console=True)

cities = ox.geocode_to_gdf(['Portugal, Lisbon', 'Portugal, Amadora'])
whole_polygon = cities.unary_union #unary union of both geometries
one_polygon = cities['geometry'].iloc[0] #geometry of just lisbon

G = ox.graph_from_polygon(whole_polygon, network_type='drive', simplify=True)
print(len(G)) #12811

# which nodes are within one_polygon?
nodes = ox.graph_to_gdfs(G, edges=False)
nodes_in_polygon = nodes[nodes.within(one_polygon)]
print(len(nodes_in_polygon)) #9734
gboeing
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  • I tested your solution and then compared the length of the nodes of only using Lisbon's network with the length of nodes I get from your method and they are different. From Lisbon's network I get 9719 nodes and from this method I get 9735. I am using the official name: 'Município de Lisboa' and 'Município da Amadora' – DPM Jul 21 '20 at 18:57