geopandas.GeoSeries.line_merge

GeoSeries.line_merge(directed=False)

Returns (Multi)LineStrings formed by combining the lines in a MultiLineString.

Lines are joined together at their endpoints in case two lines are intersecting. Lines are not joined when 3 or more lines are intersecting at the endpoints. Line elements that cannot be joined are kept as is in the resulting MultiLineString.

The direction of each merged LineString will be that of the majority of the LineStrings from which it was derived. Except if directed=True is specified, then the operation will not change the order of points within lines and so only lines which can be joined with no change in direction are merged.

Non-linear geometeries result in an empty GeometryCollection.

Parameters:

directedbool, default False

Only combine lines if possible without changing point order. Requires GEOS >= 3.11.0

Returns:

GeoSeries

Examples

>>> from shapely.geometry import MultiLineString, Point
>>> s = geopandas.GeoSeries(
...     [
...         MultiLineString([[(0, 2), (0, 10)], [(0, 10), (5, 10)]]),
...         MultiLineString([[(0, 2), (0, 10)], [(0, 11), (5, 10)]]),
...         MultiLineString(),
...         MultiLineString([[(0, 0), (1, 0)], [(0, 0), (3, 0)]]),
...         Point(0, 0),
...     ]
... )
>>> s
0    MULTILINESTRING ((0 2, 0 10), (0 10, 5 10))
1    MULTILINESTRING ((0 2, 0 10), (0 11, 5 10))
2                          MULTILINESTRING EMPTY
3       MULTILINESTRING ((0 0, 1 0), (0 0, 3 0))
4                                    POINT (0 0)
dtype: geometry

>>> s.line_merge()
0                   LINESTRING (0 2, 0 10, 5 10)
1    MULTILINESTRING ((0 2, 0 10), (0 11, 5 10))
2                       GEOMETRYCOLLECTION EMPTY
3                     LINESTRING (1 0, 0 0, 3 0)
4                       GEOMETRYCOLLECTION EMPTY
dtype: geometry

With directed=True, you can avoid changing the order of points within lines and merge only lines where no change of direction is required:

>>> s.line_merge(directed=True)
0                   LINESTRING (0 2, 0 10, 5 10)
1    MULTILINESTRING ((0 2, 0 10), (0 11, 5 10))
2                       GEOMETRYCOLLECTION EMPTY
3       MULTILINESTRING ((0 0, 1 0), (0 0, 3 0))
4                       GEOMETRYCOLLECTION EMPTY
dtype: geometry