Add example for OR condition in custom filter

[EwoutH]

I would be curious on how to do more advanced custom filters, for example how to combine two (in and OR fasion).

custom_filter = '["highway"~"motorway|motorway_link"]'
construction_filter = '["construction"~"motorway|motorway_link"]'
full_filter = ???

Possible syntax and examples of more advanced custom filter could be added to 08-custom-filters-infrastructure.ipynb

[EwoutH]

Taking a look back at an old notebook I once applied this trick:

road_types = '["highway"~"motorway|trunk|primary|secondary|tertiary|motorway_link|trunk_link|primary_link|secondary_link|tertiary_link|construction"]["construction"!~"unclassified|residential|living_street|road|raceway|pedestrian|service|track|bridleway|cycleway|footway|path|steps"]'

But I think this should be able to done more elegant and robust.

[gboeing]

So an Overpass Turbo query to perform a union operation looks something like this:

(way["railway"="light_rail"]({{bbox}});way["highway"="primary"]({{bbox}}););(._;>;);out;

This example will return all the ways tagged railway=light_rail and all the ways tagged highway=primary. As you might notice, this doesn't work with the OSMnx custom_filter function argument, because that argument is only the ["railway"="light_rail"] or the ["highway"="primary"] part of the above query.

So then how to you create a graph of the union of multiple infrastructure types? See here and here. The short story is you use networkx.compose like:

import networkx as nx
import osmnx as ox
place = 'Some City'
G1 = ox.graph_from_place(place, custom_filter='["highway"~"primary"]')
G2 = ox.graph_from_place(place, custom_filter='["railway"~"light_rail"]')
G = nx.compose(G1, G2)

This will generate essentially the same result as the OverpassQL union above.

All that said, it's worth noting that the OSMnx features module allows you to pass a tags dict argument that does allow unions in the query. The graph module in contrast queries by predefined network_type strings or by inserting a single custom_filter string into the query. It may be possible to enhance the graph module's functions to accept a tags argument (perhaps instead of the custom_filter argument), like the features module does. But that functionality doesn't currently exist and its feasibility has not been verified.

[gboeing]

See also gboeing/osmnx#1199

[HDKMP]

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[gboeing]

I will add an example here next time I update the repo to demonstrate the enhancement (gboeing/osmnx#1204) of passing a list to custom_filter to perform a union of multiple queries.