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"""Module to clip vector data using GeoPandas."""
import warnings
import numpy as np
import pandas.api.types
from shapely.geometry import MultiPolygon, Polygon, box
from geopandas import GeoDataFrame, GeoSeries
from geopandas.array import (
LINE_GEOM_TYPES,
POINT_GEOM_TYPES,
POLYGON_GEOM_TYPES,
_check_crs,
_crs_mismatch_warn,
)
def _mask_is_list_like_rectangle(mask):
"""
Check if the input mask is list-like and not an instance of
specific geometric types.
Parameters
----------
mask : GeoDataFrame, GeoSeries, (Multi)Polygon, list-like
Polygon vector layer used to clip ``gdf``.
Returns
-------
bool
True if `mask` is list-like and not an instance of `GeoDataFrame`,
`GeoSeries`, `Polygon`, or `MultiPolygon`, otherwise False.
"""
return pandas.api.types.is_list_like(mask) and not isinstance(
mask, GeoDataFrame | GeoSeries | Polygon | MultiPolygon
)
def _clip_gdf_with_mask(gdf, mask, sort=False):
"""
Clip geometry to the polygon/rectangle extent.
Clip an input GeoDataFrame to the polygon extent of the polygon
parameter.
Parameters
----------
gdf : GeoDataFrame, GeoSeries
Dataframe to clip.
mask : (Multi)Polygon, list-like
Reference polygon/rectangle for clipping.
sort : boolean, default False
If True, the results will be sorted in ascending order using the
geometries' indexes as the primary key.
Returns
-------
GeoDataFrame
The returned GeoDataFrame is a clipped subset of gdf
that intersects with polygon/rectangle.
"""
clipping_by_rectangle = _mask_is_list_like_rectangle(mask)
if clipping_by_rectangle:
intersection_polygon = box(*mask)
else:
intersection_polygon = mask
gdf_sub = gdf.iloc[
gdf.sindex.query(intersection_polygon, predicate="intersects", sort=sort)
]
# For performance reasons points don't need to be intersected with poly
non_point_mask = gdf_sub.geom_type != "Point"
if not non_point_mask.any():
# only points, directly return
return gdf_sub
# Clip the data with the polygon
if isinstance(gdf_sub, GeoDataFrame):
clipped = gdf_sub.copy()
if clipping_by_rectangle:
clipped.loc[non_point_mask, clipped._geometry_column_name] = (
gdf_sub.geometry.values[non_point_mask].clip_by_rect(*mask)
)
else:
clipped.loc[non_point_mask, clipped._geometry_column_name] = (
gdf_sub.geometry.values[non_point_mask].intersection(mask)
)
else:
# GeoSeries
clipped = gdf_sub.copy()
if clipping_by_rectangle:
clipped[non_point_mask] = gdf_sub.values[non_point_mask].clip_by_rect(*mask)
else:
clipped[non_point_mask] = gdf_sub.values[non_point_mask].intersection(mask)
if clipping_by_rectangle:
# clip_by_rect might return empty geometry collections in edge cases
clipped = clipped[~clipped.is_empty]
return clipped
def clip(gdf, mask, keep_geom_type=False, sort=False):
"""Clip points, lines, or polygon geometries to the mask extent.
Both layers must be in the same Coordinate Reference System (CRS).
The ``gdf`` will be clipped to the full extent of the clip object.
If there are multiple polygons in mask, data from ``gdf`` will be
clipped to the total boundary of all polygons in mask.
If the ``mask`` is list-like with four elements ``(minx, miny, maxx, maxy)``, a
faster rectangle clipping algorithm will be used. Note that this can lead to
slightly different results in edge cases, e.g. if a line would be reduced to a
point, this point might not be returned.
The geometry is clipped in a fast but possibly dirty way. The output is not
guaranteed to be valid. No exceptions will be raised for topological errors.
Parameters
----------
gdf : GeoDataFrame or GeoSeries
Vector layer (point, line, polygon) to be clipped to mask.
mask : GeoDataFrame, GeoSeries, (Multi)Polygon, list-like
Polygon vector layer used to clip ``gdf``.
The mask's geometry is dissolved into one geometric feature
and intersected with ``gdf``.
If the mask is list-like with four elements ``(minx, miny, maxx, maxy)``,
``clip`` will use a faster rectangle clipping (:meth:`~GeoSeries.clip_by_rect`),
possibly leading to slightly different results.
keep_geom_type : boolean, default False
If True, return only geometries of original type in case of intersection
resulting in multiple geometry types or GeometryCollections.
If False, return all resulting geometries (potentially mixed-types).
sort : boolean, default False
If True, the results will be sorted in ascending order using the
geometries' indexes as the primary key.
Returns
-------
GeoDataFrame or GeoSeries
Vector data (points, lines, polygons) from ``gdf`` clipped to
polygon boundary from mask.
See Also
--------
GeoDataFrame.clip : equivalent GeoDataFrame method
GeoSeries.clip : equivalent GeoSeries method
Examples
--------
Clip points (grocery stores) with polygons (the Near West Side community):
>>> import geodatasets
>>> chicago = geopandas.read_file(
... geodatasets.get_path("geoda.chicago_health")
... )
>>> near_west_side = chicago[chicago["community"] == "NEAR WEST SIDE"]
>>> groceries = geopandas.read_file(
... geodatasets.get_path("geoda.groceries")
... ).to_crs(chicago.crs)
>>> groceries.shape
(148, 8)
>>> nws_groceries = geopandas.clip(groceries, near_west_side)
>>> nws_groceries.shape
(7, 8)
"""
if not isinstance(gdf, GeoDataFrame | GeoSeries):
raise TypeError(f"'gdf' should be GeoDataFrame or GeoSeries, got {type(gdf)}")
clipping_by_rectangle = _mask_is_list_like_rectangle(mask)
if (
not isinstance(mask, GeoDataFrame | GeoSeries | Polygon | MultiPolygon)
and not clipping_by_rectangle
):
raise TypeError(
"'mask' should be GeoDataFrame, GeoSeries,"
f"(Multi)Polygon or list-like, got {type(mask)}"
)
if clipping_by_rectangle and len(mask) != 4:
raise TypeError(
"If 'mask' is list-like, it must have four values (minx, miny, maxx, maxy)"
)
if isinstance(mask, GeoDataFrame | GeoSeries):
if not _check_crs(gdf, mask):
_crs_mismatch_warn(gdf, mask, stacklevel=3)
if isinstance(mask, GeoDataFrame | GeoSeries):
box_mask = mask.total_bounds
elif clipping_by_rectangle:
box_mask = mask
else:
# Avoid empty tuple returned by .bounds when geometry is empty. A tuple of
# all nan values is consistent with the behavior of
# {GeoSeries, GeoDataFrame}.total_bounds for empty geometries.
# TODO(shapely) can simpely use mask.bounds once relying on Shapely 2.0
box_mask = mask.bounds if not mask.is_empty else (np.nan,) * 4
box_gdf = gdf.total_bounds
if not (
((box_mask[0] <= box_gdf[2]) and (box_gdf[0] <= box_mask[2]))
and ((box_mask[1] <= box_gdf[3]) and (box_gdf[1] <= box_mask[3]))
):
return gdf.iloc[:0]
if isinstance(mask, GeoDataFrame | GeoSeries):
combined_mask = mask.geometry.union_all()
else:
combined_mask = mask
clipped = _clip_gdf_with_mask(gdf, combined_mask, sort=sort)
if keep_geom_type:
geomcoll_concat = (clipped.geom_type == "GeometryCollection").any()
geomcoll_orig = (gdf.geom_type == "GeometryCollection").any()
new_collection = geomcoll_concat and not geomcoll_orig
if geomcoll_orig:
warnings.warn(
"keep_geom_type can not be called on a "
"GeoDataFrame with GeometryCollection.",
stacklevel=2,
)
else:
# Check that the gdf for multiple geom types (points, lines and/or polys)
orig_types_total = sum(
[
gdf.geom_type.isin(POLYGON_GEOM_TYPES).any(),
gdf.geom_type.isin(LINE_GEOM_TYPES).any(),
gdf.geom_type.isin(POINT_GEOM_TYPES).any(),
]
)
# Check how many geometry types are in the clipped GeoDataFrame
clip_types_total = sum(
[
clipped.geom_type.isin(POLYGON_GEOM_TYPES).any(),
clipped.geom_type.isin(LINE_GEOM_TYPES).any(),
clipped.geom_type.isin(POINT_GEOM_TYPES).any(),
]
)
# Check there aren't any new geom types in the clipped GeoDataFrame
more_types = orig_types_total < clip_types_total
if orig_types_total > 1:
warnings.warn(
"keep_geom_type can not be called on a mixed type GeoDataFrame.",
stacklevel=2,
)
elif new_collection or more_types:
orig_type = gdf.geom_type.iloc[0]
if new_collection:
clipped = clipped.explode(index_parts=False)
if orig_type in POLYGON_GEOM_TYPES:
clipped = clipped.loc[clipped.geom_type.isin(POLYGON_GEOM_TYPES)]
elif orig_type in LINE_GEOM_TYPES:
clipped = clipped.loc[clipped.geom_type.isin(LINE_GEOM_TYPES)]
return clipped
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