Finding isolated networks¶

Functions for Finding network components in a GeoDataFrame of lines.

get_component_size(gdf)[source]

Finds the size of each component in the network.

Takes a GeoDataFrame of linea and creates the column “component_size”, which indicates the size of the network component the line is a part of.

Parameters:: gdf (GeoDataFrame) – a GeoDataFrame of lines.
Return type:: GeoDataFrame
Returns:: A GeoDataFrame with a new column “component_size”.

Examples:¶

>>> from sgis import read_parquet_url, get_component_size
>>> roads = read_parquet_url("https://media.githubusercontent.com/media/statisticsnorway/ssb-sgis/main/tests/testdata/roads_oslo_2022.parquet")

>>> roads = get_component_size(roads)
>>> roads["component_size"].value_counts().head()
component_size
79180    85638
2         1601
4          688
6          406
3          346
Name: count, dtype: int64

get_connected_components(gdf)[source]

Finds the largest network component.

It takes a GeoDataFrame of lines and finds the lines that are part of the largest connected network component. These lines are given the value 1 in the added column ‘connected’, while isolated network islands get the value 0.

Uses the connected_components function from the networkx package.

Parameters:: gdf (GeoDataFrame) – A GeoDataFrame of lines.
Return type:: GeoDataFrame
Returns:: The GeoDataFrame with a new column “connected”.

Examples:¶

>>> from sgis import read_parquet_url, get_connected_components
>>> roads = read_parquet_url("https://media.githubusercontent.com/media/statisticsnorway/ssb-sgis/main/tests/testdata/roads_oslo_2022.parquet")

>>> roads = get_connected_components(roads)
>>> roads.connected.value_counts()
1.0    85638
0.0     7757
Name: connected, dtype: int64

Removing the isolated network islands.

>>> connected_roads = get_connected_components(roads).loc[lambda x: x["connected"] == 1]
>>> roads.connected.value_counts()
1.0    85638
Name: connected, dtype: int64