diff --git a/doc/docs.rst b/doc/docs.rst index 7ff4446..92c0bca 100644 --- a/doc/docs.rst +++ b/doc/docs.rst @@ -208,6 +208,19 @@ Additionally, the following methods are implemented: Load a ``GeoSeries`` from a file from any format recognized by `fiona`_. +.. method:: GeoSeries.to_crs(crs=None, epsg=None) + + Transform all geometries in a GeoSeries to a different coordinate + reference system. The ``crs`` attribute on the current GeoSeries + must be set. Either ``crs`` in dictionary form or an EPSG code may + be specified for output. + + This method will transform all points in all objects. It has no + notion or projecting entire geometries. All segments joining points + are assumed to be lines in the current projection, not geodesics. + Objects crossing the dateline (or other projection boundary) will + have undesirable behavior. + .. method:: GeoSeries.plot(colormap='Set1') Generate a plot of the geometries in the ``GeoSeries``. @@ -235,6 +248,21 @@ Currently only the following methods are implemented for a ``GeoDataFrame``: Load a ``GeoDataFrame`` from a file from any format recognized by `fiona`_. +.. method:: GeoSeries.to_crs(crs=None, epsg=None, inplace=False) + + Transform all geometries in the ``geometry`` column of a + GeoDataFrame to a different coordinate reference system. The + ``crs`` attribute on the current GeoSeries must be set. Either + ``crs`` in dictionary form or an EPSG code may be specified for + output. If ``inplace=True`` the geometry column will be replaced in + the current dataframe, otherwise a new GeoDataFrame will be returned. + + This method will transform all points in all objects. It has no + notion or projecting entire geometries. All segments joining points + are assumed to be lines in the current projection, not geodesics. + Objects crossing the dateline (or other projection boundary) will + have undesirable behavior. + .. method:: GeoDataFrame.plot() Generate a plot of the geometries in the ``GeoDataFrame``. diff --git a/geopandas/geodataframe.py b/geopandas/geodataframe.py index 82298a5..3d95caa 100644 --- a/geopandas/geodataframe.py +++ b/geopandas/geodataframe.py @@ -71,6 +71,25 @@ class GeoDataFrame(DataFrame): 'features': [feature(i, row) for i, row in self.iterrows()]}, **kwargs ) + def to_crs(self, crs=None, epsg=None, inplace=False): + """Transform geometries to a new coordinate reference system + + This method will transform all points in all objects. It has + no notion or projecting entire geometries. All segments + joining points are assumed to be lines in the current + projection, not geodesics. Objects crossing the dateline (or + other projection boundary) will have undesirable behavior. + """ + if inplace: + df = self + else: + df = self.copy() + df.crs = self.crs + geom = df.geometry.to_crs(crs=crs, epsg=epsg) + df.geometry = geom + if not inplace: + return df + def __getitem__(self, key): """ The geometry column is not stored as a GeoSeries, so need to make sure diff --git a/geopandas/geoseries.py b/geopandas/geoseries.py index f8c7cd7..4bb8607 100644 --- a/geopandas/geoseries.py +++ b/geopandas/geoseries.py @@ -1,13 +1,16 @@ from warnings import warn +from functools import partial import numpy as np from pandas import Series, DataFrame +import pyproj from shapely.geometry import shape, Polygon, Point from shapely.geometry.collection import GeometryCollection from shapely.geometry.base import BaseGeometry -from shapely.ops import cascaded_union, unary_union +from shapely.ops import cascaded_union, unary_union, transform import fiona +from fiona.crs import from_epsg from plotting import plot_series @@ -380,3 +383,32 @@ class GeoSeries(Series): def plot(self, *args, **kwargs): return plot_series(self, *args, **kwargs) + + # + # Additional methods + # + + def to_crs(self, crs=None, epsg=None): + """Transform geometries to a new coordinate reference system + + This method will transform all points in all objects. It has + no notion or projecting entire geometries. All segments + joining points are assumed to be lines in the current + projection, not geodesics. Objects crossing the dateline (or + other projection boundary) will have undesirable behavior. + """ + if self.crs is None: + raise ValueError('Cannot transform naive geometries. ' + 'Please set a crs on the object first.') + if crs is None: + try: + crs = from_epsg(epsg) + except TypeError: + raise TypeError('Must set either crs or epsg for output.') + proj_in = pyproj.Proj(**self.crs) + proj_out = pyproj.Proj(**crs) + project = partial(pyproj.transform, proj_in, proj_out) + result = self.apply(lambda geom: transform(project, geom)) + result.__class__ = GeoSeries + result.crs = crs + return result diff --git a/tests/test_geoseries.py b/tests/test_geoseries.py index 7287bfe..00bd2c0 100644 --- a/tests/test_geoseries.py +++ b/tests/test_geoseries.py @@ -29,6 +29,10 @@ class TestSeries(unittest.TestCase): self.a1.index = ['A', 'B'] self.a2 = self.g2.copy() self.a2.index = ['B', 'C'] + self.esb = Point(-73.9847, 40.7484) + self.sol = Point(-74.0446, 40.6893) + self.landmarks = GeoSeries([self.esb, self.sol], + crs={'init': 'epsg:4326', 'no_defs': True}) def test_area(self): assert_array_equal(self.g1.area.values, np.array([0.5, 1.0])) @@ -177,3 +181,8 @@ class TestSeries(unittest.TestCase): self.assertTrue(np.alltrue(self.g2.contains(self.g2.representative_point()))) self.assertTrue(np.alltrue(self.g3.contains(self.g3.representative_point()))) self.assertTrue(np.alltrue(self.g4.contains(self.g4.representative_point()))) + + def test_transform(self): + utm18n = self.landmarks.to_crs(epsg=26918) + lonlat = utm18n.to_crs(epsg=4326) + self.assertTrue(np.alltrue(self.landmarks.almost_equals(lonlat)))