Source code for cartopy.feature

# (C) British Crown Copyright 2011 - 2016, Met Office
# This file is part of cartopy.
# cartopy is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# cartopy is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public License
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This module defines :class:`Feature` instances, for use with


from __future__ import (absolute_import, division, print_function)

from abc import ABCMeta, abstractmethod
import os.path

import numpy as np
import shapely.geometry as sgeom
import six

import as shapereader

COLORS = {'land': np.array((240, 240, 220)) / 256.,
          'land_alt1': np.array((220, 220, 220)) / 256.,
          'water': np.array((152, 183, 226)) / 256.}
A dictionary of colors useful for drawing Features.

The named keys in this dictionary represent the "type" of
feature being plotted.


Caches a mapping between (name, category, scale) and a tuple of the
resulting geometries.

Provides a significant performance benefit (when combined with object id
caching in GeoAxes.add_geometries) when producing multiple maps of the
same projection.


[docs]class Feature(six.with_metaclass(ABCMeta)): """ Represents a collection of points, lines and polygons with convenience methods for common drawing and filtering operations. Args: * crs - the coordinate reference system of this Feature Kwargs: Keyword arguments to be used when drawing this feature. .. seealso:: To add features to the current matplotlib axes, see :func:`GeoAxes <cartopy.mpl.geoaxes.GeoAxes.add_feature>`. """ def __init__(self, crs, **kwargs): self._crs = crs self._kwargs = dict(kwargs) @property def crs(self): """The cartopy CRS for the geometries in this feature.""" return self._crs @property def kwargs(self): """ The read-only dictionary of keyword arguments that are used when creating the matplotlib artists for this feature. """ return dict(self._kwargs) @abstractmethod
[docs] def geometries(self): """ Returns an iterator of (shapely) geometries for this feature. """ pass
[docs] def intersecting_geometries(self, extent): """ Returns an iterator of shapely geometries that intersect with the given extent. The extent is assumed to be in the CRS of the feature. If extent is None, the method returns all geometries for this dataset. """ if extent is not None: extent_geom =[0], extent[2], extent[1], extent[3]) return (geom for geom in self.geometries() if extent_geom.intersects(geom)) else: return self.geometries()
[docs]class ShapelyFeature(Feature): """ A class capable of drawing a collection of shapely geometries. """ def __init__(self, geometries, crs, **kwargs): """ Args: * geometries: A collection of shapely geometries. * crs: The cartopy CRS in which the provided geometries are defined. Kwargs: Keyword arguments to be used when drawing this feature. """ super(ShapelyFeature, self).__init__(crs, **kwargs) self._geoms = tuple(geometries) def geometries(self): return iter(self._geoms)
[docs]class NaturalEarthFeature(Feature): """ A simple interface to Natural Earth shapefiles. See """ def __init__(self, category, name, scale, **kwargs): """ Args: * category: The category of the dataset, i.e. either 'cultural' or 'physical'. * name: The name of the dataset, e.g. 'admin_0_boundary_lines_land'. * scale: The dataset scale, i.e. one of '10m', '50m', or '110m'. Corresponding to 1:10,000,000, 1:50,000,000, and 1:110,000,000 respectively. Kwargs: Keyword arguments to be used when drawing this feature. """ super(NaturalEarthFeature, self).__init__(, **kwargs) self.category = category = name self.scale = scale def geometries(self): key = (, self.category, self.scale) if key not in _NATURAL_EARTH_GEOM_CACHE: path = shapereader.natural_earth(resolution=self.scale, category=self.category, geometries = tuple(shapereader.Reader(path).geometries()) _NATURAL_EARTH_GEOM_CACHE[key] = geometries else: geometries = _NATURAL_EARTH_GEOM_CACHE[key] return iter(geometries)
[docs]class GSHHSFeature(Feature): """ An interface to the GSHHS dataset. See Args: * scale: The dataset scale. One of 'auto', 'coarse', 'low', 'intermediate', 'high, or 'full' (default is 'auto'). * levels: A list of integers 1-4 corresponding to the desired GSHHS feature levels to draw (default is [1] which corresponds to coastlines). Kwargs: Keyword arguments to be used when drawing the feature. Defaults are edgecolor='black' and facecolor='none'. """ _geometries_cache = {} """ A mapping from scale and level to GSHHS shapely geometry:: {(scale, level): geom} This provides a perfomance boost when plotting in interactive mode or instantiating multiple GSHHS artists, by reducing repeated file IO. """ def __init__(self, scale='auto', levels=None, **kwargs): super(GSHHSFeature, self).__init__(, **kwargs) if scale not in ('auto', 'a', 'coarse', 'c', 'low', 'l', 'intermediate', 'i', 'high', 'h', 'full', 'f'): raise ValueError("Unknown GSHHS scale '{}'.".format(scale)) self._scale = scale if levels is None: levels = [1] self._levels = set(levels) unknown_levels = self._levels.difference([1, 2, 3, 4]) if unknown_levels: raise ValueError("Unknown GSHHS levels " "'{}'.".format(unknown_levels)) # Default kwargs self._kwargs.setdefault('edgecolor', 'black') self._kwargs.setdefault('facecolor', 'none') def _scale_from_extent(self, extent): """ Returns the appropriate scale (e.g. 'i') for the given extent expressed in PlateCarree CRS. """ # Default to coarse scale scale = 'c' if extent is not None: # Upper limit on extent in degrees. scale_limits = (('c', 20.0), ('l', 10.0), ('i', 2.0), ('h', 0.5), ('f', 0.1)) width = abs(extent[1] - extent[0]) height = abs(extent[3] - extent[2]) min_extent = min(width, height) if min_extent != 0: for scale, limit in scale_limits: if min_extent > limit: break return scale def geometries(self): return self.intersecting_geometries(extent=None) def intersecting_geometries(self, extent): if self._scale == 'auto': scale = self._scale_from_extent(extent) else: scale = self._scale[0] if extent is not None: extent_geom =[0], extent[2], extent[1], extent[3]) for level in self._levels: geoms = GSHHSFeature._geometries_cache.get((scale, level)) if geoms is None: # Load GSHHS geometries from appropriate shape file. # TODO selective load based on bbox of each geom in file. path = shapereader.gshhs(scale, level) geoms = tuple(shapereader.Reader(path).geometries()) GSHHSFeature._geometries_cache[(scale, level)] = geoms for geom in geoms: if extent is None or extent_geom.intersects(geom): yield geom
class WFSFeature(Feature): """ A class capable of drawing a collection of geometries obtained from an OGC Web Feature Service (WFS). This feature requires additional dependencies. If installed via pip, try ``pip install cartopy[ows]``. """ def __init__(self, wfs, features, **kwargs): """ Args: * wfs: string or :class:`owslib.wfs.WebFeatureService` instance The WebFeatureService instance, or URL of a WFS service, from which to retrieve the geometries. * features: string or list of strings The typename(s) of features available from the web service that will be retrieved. Somewhat analogous to layers in WMS/WMTS. Kwargs: Keyword arguments to be used when drawing this feature. """ try: from import WFSGeometrySource except ImportError as e: six.raise_from(ImportError( 'WFSFeature requires additional dependencies. If installed ' 'via pip, try `pip install cartopy[ows]`.\n'), e) self.source = WFSGeometrySource(wfs, features) crs = self.source.default_projection() super(WFSFeature, self).__init__(crs, **kwargs) # Default kwargs self._kwargs.setdefault('edgecolor', 'black') self._kwargs.setdefault('facecolor', 'none') def geometries(self): min_x, min_y, max_x, max_y = geoms = self.source.fetch_geometries(, extent=(min_x, max_x, min_y, max_y)) return iter(geoms) def intersecting_geometries(self, extent): geoms = self.source.fetch_geometries(, extent) return iter(geoms) BORDERS = NaturalEarthFeature('cultural', 'admin_0_boundary_lines_land', '110m', edgecolor='black', facecolor='none') """Small scale (1:110m) country boundaries.""" COASTLINE = NaturalEarthFeature('physical', 'coastline', '110m', edgecolor='black', facecolor='none') """Small scale (1:110m) coastline, including major islands.""" LAKES = NaturalEarthFeature('physical', 'lakes', '110m', edgecolor='face', facecolor=COLORS['water']) """Small scale (1:110m) natural and artificial lakes.""" LAND = NaturalEarthFeature('physical', 'land', '110m', edgecolor='face', facecolor=COLORS['land']) """Small scale (1:110m) land polygons, including major islands.""" OCEAN = NaturalEarthFeature('physical', 'ocean', '110m', edgecolor='face', facecolor=COLORS['water']) """Small scale (1:110m) ocean polygons.""" RIVERS = NaturalEarthFeature('physical', 'rivers_lake_centerlines', '110m', edgecolor=COLORS['water'], facecolor='none') """Small scale (1:110m) single-line drainages, including lake centerlines."""