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|
"""
geopandas.clip
==============
A module to clip vector data using GeoPandas.
"""
import warnings
import numpy as np
import pandas as pd
from shapely.geometry import Polygon, MultiPolygon
from geopandas import GeoDataFrame, GeoSeries
from geopandas.array import _check_crs, _crs_mismatch_warn
def _clip_points(gdf, poly):
"""Clip point geometry to the polygon extent.
Clip an input point GeoDataFrame to the polygon extent of the poly
parameter. Points that intersect the poly geometry are extracted with
associated attributes and returned.
Parameters
----------
gdf : GeoDataFrame, GeoSeries
Composed of point geometry that will be clipped to the poly.
poly : (Multi)Polygon
Reference geometry used to spatially clip the data.
Returns
-------
GeoDataFrame
The returned GeoDataFrame is a subset of gdf that intersects
with poly.
"""
return gdf.iloc[gdf.sindex.query(poly, predicate="intersects")]
def _clip_line_poly(gdf, poly):
"""Clip line and polygon geometry to the polygon extent.
Clip an input line or polygon to the polygon extent of the poly
parameter. Parts of Lines or Polygons that intersect the poly geometry are
extracted with associated attributes and returned.
Parameters
----------
gdf : GeoDataFrame, GeoSeries
Line or polygon geometry that is clipped to poly.
poly : (Multi)Polygon
Reference polygon for clipping.
Returns
-------
GeoDataFrame
The returned GeoDataFrame is a clipped subset of gdf
that intersects with poly.
"""
gdf_sub = gdf.iloc[gdf.sindex.query(poly, predicate="intersects")]
# Clip the data with the polygon
if isinstance(gdf_sub, GeoDataFrame):
clipped = gdf_sub.copy()
clipped["geometry"] = gdf_sub.intersection(poly)
else:
# GeoSeries
clipped = gdf_sub.intersection(poly)
return clipped
def clip(gdf, mask, keep_geom_type=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.
Parameters
----------
gdf : GeoDataFrame or GeoSeries
Vector layer (point, line, polygon) to be clipped to mask.
mask : GeoDataFrame, GeoSeries, (Multi)Polygon
Polygon vector layer used to clip `gdf`.
The mask's geometry is dissolved into one geometric feature
and intersected with `gdf`.
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).
Returns
-------
GeoDataFrame or GeoSeries
Vector data (points, lines, polygons) from `gdf` clipped to
polygon boundary from mask.
Examples
--------
Clip points (global cities) with a polygon (the South American continent):
>>> import geopandas
>>> path =
>>> world = geopandas.read_file(
... geopandas.datasets.get_path('naturalearth_lowres'))
>>> south_america = world[world['continent'] == "South America"]
>>> capitals = geopandas.read_file(
... geopandas.datasets.get_path('naturalearth_cities'))
>>> capitals.shape
(202, 2)
>>> sa_capitals = geopandas.clip(capitals, south_america)
>>> sa_capitals.shape
(12, 2)
"""
if not isinstance(gdf, (GeoDataFrame, GeoSeries)):
raise TypeError(
"'gdf' should be GeoDataFrame or GeoSeries, got {}".format(type(gdf))
)
if not isinstance(mask, (GeoDataFrame, GeoSeries, Polygon, MultiPolygon)):
raise TypeError(
"'mask' should be GeoDataFrame, GeoSeries or"
"(Multi)Polygon, got {}".format(type(gdf))
)
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
else:
box_mask = mask.bounds
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)):
poly = mask.geometry.unary_union
else:
poly = mask
geom_types = gdf.geometry.type
poly_idx = np.asarray((geom_types == "Polygon") | (geom_types == "MultiPolygon"))
line_idx = np.asarray(
(geom_types == "LineString")
| (geom_types == "LinearRing")
| (geom_types == "MultiLineString")
)
point_idx = np.asarray((geom_types == "Point") | (geom_types == "MultiPoint"))
geomcoll_idx = np.asarray((geom_types == "GeometryCollection"))
if point_idx.any():
point_gdf = _clip_points(gdf[point_idx], poly)
else:
point_gdf = None
if poly_idx.any():
poly_gdf = _clip_line_poly(gdf[poly_idx], poly)
else:
poly_gdf = None
if line_idx.any():
line_gdf = _clip_line_poly(gdf[line_idx], poly)
else:
line_gdf = None
if geomcoll_idx.any():
geomcoll_gdf = _clip_line_poly(gdf[geomcoll_idx], poly)
else:
geomcoll_gdf = None
order = pd.Series(range(len(gdf)), index=gdf.index)
concat = pd.concat([point_gdf, line_gdf, poly_gdf, geomcoll_gdf])
if keep_geom_type:
geomcoll_concat = (concat.geom_type == "GeometryCollection").any()
geomcoll_orig = geomcoll_idx.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."
)
else:
polys = ["Polygon", "MultiPolygon"]
lines = ["LineString", "MultiLineString", "LinearRing"]
points = ["Point", "MultiPoint"]
# Check that the gdf for multiple geom types (points, lines and/or polys)
orig_types_total = sum(
[
gdf.geom_type.isin(polys).any(),
gdf.geom_type.isin(lines).any(),
gdf.geom_type.isin(points).any(),
]
)
# Check how many geometry types are in the clipped GeoDataFrame
clip_types_total = sum(
[
concat.geom_type.isin(polys).any(),
concat.geom_type.isin(lines).any(),
concat.geom_type.isin(points).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."
)
elif new_collection or more_types:
orig_type = gdf.geom_type.iloc[0]
if new_collection:
concat = concat.explode()
if orig_type in polys:
concat = concat.loc[concat.geom_type.isin(polys)]
elif orig_type in lines:
concat = concat.loc[concat.geom_type.isin(lines)]
# Return empty GeoDataFrame or GeoSeries if no shapes remain
if len(concat) == 0:
return gdf.iloc[:0]
# Preserve the original order of the input
if isinstance(concat, GeoDataFrame):
concat["_order"] = order
return concat.sort_values(by="_order").drop(columns="_order")
else:
concat = GeoDataFrame(geometry=concat)
concat["_order"] = order
return concat.sort_values(by="_order").geometry
|
