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import pandas as pd
from shapely.geometry import MultiLineString, MultiPoint, MultiPolygon
from shapely.geometry.base import BaseGeometry
_multi_type_map = {
"Point": MultiPoint,
"LineString": MultiLineString,
"Polygon": MultiPolygon,
}
def collect(x, multi=False):
"""Collect single part geometries into their Multi* counterpart.
Parameters
----------
x : an iterable or Series of Shapely geometries, a GeoSeries, or
a single Shapely geometry
multi : boolean, default False
if True, force returned geometries to be Multi* even if they
only have one component.
"""
if isinstance(x, BaseGeometry):
x = [x]
elif isinstance(x, pd.Series):
x = list(x)
# We cannot create GeometryCollection here so all types
# must be the same. If there is more than one element,
# they cannot be Multi*, i.e., can't pass in combination of
# Point and MultiPoint... or even just MultiPoint
t = x[0].geom_type
if not all(g.geom_type == t for g in x):
raise ValueError("Geometry type must be homogeneous")
if len(x) > 1 and t.startswith("Multi"):
raise ValueError(f"Cannot collect {t}. Must have single geometries")
if len(x) == 1 and (t.startswith("Multi") or not multi):
# If there's only one single part geom and we're not forcing to
# multi, then just return it
return x[0]
return _multi_type_map[t](x)
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