GeoJSON的python支持库。

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2016-04. | * IETF标准项目：https://github.com/geojson | * PyPi支持库: https://pypi.python.org/pypi/geojson | * 其它的支持库包括：GeoPandas, Shaply, GDAL, GIScript

In [9]:

from pprint import *

Installation

python-geojson is compatible with Python 2.6, 2.7, 3.2, 3.3, and 3.4. It is listed on PyPi as ‘geojson’. The recommended way to install is via pip:

pip install geojson

GeoJSON Objects

This library implements all the GeoJSON Objects described in The GeoJSON Format Specification.

Point

In [4]:

from geojson import Point

Point((-115.81, 37.24))  # doctest: +ELLIPSIS

Out[4]:

{"coordinates": [-115.81, 37.24], "type": "Point"}

Visualize the result of the example above here. General information about Point can be found in Section 2.1.2 and Appendix A: Point within The GeoJSON Format Specification. ## MultiPoint

In [5]:

from geojson import MultiPoint

MultiPoint([(-155.52, 19.61), (-156.22, 20.74), (-157.97, 21.46)])  # doctest: +ELLIPSIS
#{"coordinates": [[-155.5..., 19.6...], [-156.2..., 20.7...], [-157.9..., 21.4...]], "type": "MultiPoint"}

Out[5]:

{"coordinates": [[-155.52, 19.61], [-156.22, 20.74], [-157.97, 21.46]], "type": "MultiPoint"}

Visualize the result of the example above here. General information about MultiPoint can be found in Section 2.1.3 and Appendix A: MultiPoint within The GeoJSON Format Specification. ## LineString

In [11]:

from geojson import LineString

lstring = LineString([(8.919, 44.4074), (8.923, 44.4075)])  # doctest: +ELLIPSIS
#{"coordinates": [[8.91..., 44.407...], [8.92..., 44.407...]], "type": "LineString"}

pprint(lstring)

{"coordinates": [[8.919, 44.4074], [8.923, 44.4075]], "type": "LineString"}

Visualize the result of the example above here. General information about LineString can be found in Section 2.1.4 and Appendix A: LineString within The GeoJSON Format Specification. ## MultiLineString

In [10]:

from geojson import MultiLineString

mlstring = MultiLineString([
[(3.75, 9.25), (-130.95, 1.52)],
[(23.15, -34.25), (-1.35, -4.65), (3.45, 77.95)]
])  # doctest: +ELLIPSIS
#{"coordinates": [[[3.7..., 9.2...], [-130.9..., 1.52...]], [[23.1..., -34.2...],
#[-1.3..., -4.6...], [3.4..., 77.9...]]], "type": "MultiLineString"}

pprint(mlstring)

{'coordinates': [[(3.75, 9.25), (-130.95, 1.52)],
                 [(23.15, -34.25), (-1.35, -4.65), (3.45, 77.95)]],
 'type': 'MultiLineString'}

Visualize the result of the example above here. General information about MultiLineString can be found in Section 2.1.5 and Appendix A: MultiLineString within The GeoJSON Format Specification. ## Polygon

In [16]:

from geojson import Polygon

# no hole within polygon
polya = Polygon([[(2.38, 57.322), (23.194, -20.28), (-120.43, 19.15), (2.38, 57.322)]])  # doctest: +ELLIPSIS
#{"coordinates": [[[2.3..., 57.32...], [23.19..., -20.2...], [-120.4..., 19.1...]]], "type": "Polygon"}

pprint(polya)

# hole within polygon
polyb = Polygon([
[(2.38, 57.322), (23.194, -20.28), (-120.43, 19.15), (2.38, 57.322)],
[(-5.21, 23.51), (15.21, -10.81), (-20.51, 1.51), (-5.21, 23.51)]
])  # doctest: +ELLIPSIS
#{"coordinates": [[[2.3..., 57.32...], [23.19..., -20.2...], [-120.4..., 19.1...]],
#[[-5.2..., 23.5...], [15.2..., -10.8...], [-20.5..., 1.5...], [-5.2..., 23.5...]]], "type": "Polygon"}

pprint(polyb)

{'coordinates': [[(2.38, 57.322),
                  (23.194, -20.28),
                  (-120.43, 19.15),
                  (2.38, 57.322)]],
 'type': 'Polygon'}
{'coordinates': [[(2.38, 57.322),
                  (23.194, -20.28),
                  (-120.43, 19.15),
                  (2.38, 57.322)],
                 [(-5.21, 23.51),
                  (15.21, -10.81),
                  (-20.51, 1.51),
                  (-5.21, 23.51)]],
 'type': 'Polygon'}

Visualize the results of the example above here. General information about Polygon can be found in Section 2.1.6 and Appendix A: Polygon within The GeoJSON Format Specification. ## MultiPolygon

In [18]:

from geojson import MultiPolygon

mp = MultiPolygon([
([(3.78, 9.28), (-130.91, 1.52), (35.12, 72.234), (3.78, 9.28)],),
([(23.18, -34.29), (-1.31, -4.61), (3.41, 77.91), (23.18, -34.29)],)
])  # doctest: +ELLIPSIS

#{"coordinates": [[[[3.7..., 9.2...], [-130.9..., 1.5...], [35.1..., 72.23...]]],
#[[[23.1..., -34.2...], [-1.3..., #-4.6...], [3.4..., 77.9...]]]], "type": "MultiPolygon"}

pprint(mp)

{'coordinates': [([(3.78, 9.28),
                   (-130.91, 1.52),
                   (35.12, 72.234),
                   (3.78, 9.28)],),
                 ([(23.18, -34.29),
                   (-1.31, -4.61),
                   (3.41, 77.91),
                   (23.18, -34.29)],)],
 'type': 'MultiPolygon'}

Visualize the result of the example above here. General information about MultiPolygon can be found in Section 2.1.7 and Appendix A: MultiPolygon within The GeoJSON Format Specification. ## GeometryCollection

In [19]:

from geojson import GeometryCollection, Point, LineString

my_point = Point((23.532, -63.12))

my_line = LineString([(-152.62, 51.21), (5.21, 10.69)])

gc = GeometryCollection([my_point, my_line])  # doctest: +ELLIPSIS
#{"geometries": [{"coordinates": [23.53..., -63.1...], "type": "Point"},
#{"coordinates": [[-152.6..., 51.2...], [5.2..., 10.6...]], "type": "LineString"}], "type": "GeometryCollection"}

pprint(gc)

{'geometries': [{"coordinates": [23.532, -63.12], "type": "Point"},
                {'coordinates': [(-152.62, 51.21), (5.21, 10.69)],
                 'type': 'LineString'}],
 'type': 'GeometryCollection'}

Visualize the result of the example above here. General information about GeometryCollection can be found in Section 2.1.8 and Appendix A: GeometryCollection within The GeoJSON Format Specification. ## Feature

In [20]:

from geojson import Feature, Point

my_point = Point((-3.68, 40.41))

f1 = Feature(geometry=my_point)  # doctest: +ELLIPSIS
#{"geometry": {"coordinates": [-3.68..., 40.4...], "type": "Point"}, "properties": {}, "type": "Feature"}
pprint(f1)

f2 = Feature(geometry=my_point, properties={"country": "Spain"})  # doctest: +ELLIPSIS
#{"geometry": {"coordinates": [-3.68..., 40.4...], "type": "Point"}, "properties": {"country": "Spain"},
#"type": "Feature"}
pprint(f2)

f3 = Feature(geometry=my_point, id=27)  # doctest: +ELLIPSIS
#{"geometry": {"coordinates": [-3.68..., 40.4...], "type": "Point"}, "id": 27, "properties": {}, "type": "Feature"}
pprint(f3)

{'geometry': {"coordinates": [-3.68, 40.41], "type": "Point"},
 'properties': {},
 'type': 'Feature'}
{'geometry': {"coordinates": [-3.68, 40.41], "type": "Point"},
 'properties': {'country': 'Spain'},
 'type': 'Feature'}
{'geometry': {"coordinates": [-3.68, 40.41], "type": "Point"},
 'id': 27,
 'properties': {},
 'type': 'Feature'}

Visualize the results of the examples above here. General information about Feature can be found in Section 2.2 within The GeoJSON Format Specification. ## FeatureCollection

In [21]:

from geojson import Feature, Point, FeatureCollection

my_feature = Feature(geometry=Point((1.6432, -19.123)))

my_other_feature = Feature(geometry=Point((-80.234, -22.532)))

fc = FeatureCollection([my_feature, my_other_feature])  # doctest: +ELLIPSIS
#{"features": [{"geometry": {"coordinates": [1.643..., -19.12...], "type": "Point"}, "properties": {}, "type": #"Feature"}, {"geometry": {"coordinates": [-80.23..., -22.53...], "type": "Point"}, "properties": {}, "type": #"Feature"}], "type": "FeatureCollection"}

pprint(fc)

{'features': [{'geometry': {"coordinates": [1.6432, -19.123], "type": "Point"},
               'properties': {},
               'type': 'Feature'},
              {'geometry': {"coordinates": [-80.234, -22.532], "type": "Point"},
               'properties': {},
               'type': 'Feature'}],
 'type': 'FeatureCollection'}

Visualize the result of the example above here. General information about FeatureCollection can be found in Section 2.3 within The GeoJSON Format Specification. ## GeoJSON encoding/decoding

All of the GeoJSON Objects implemented in this library can be encoded and decoded into raw GeoJSON with the geojson.dump, geojson.dumps, geojson.load, and geojson.loads functions.

In [23]:

import geojson

my_point = geojson.Point((43.24, -1.532))

pprint(my_point)  # doctest: +ELLIPSIS
#{"coordinates": [43.2..., -1.53...], "type": "Point"}

dump = geojson.dumps(my_point, sort_keys=True)

pprint(dump)  # doctest: +ELLIPSIS
#'{"coordinates": [43.2..., -1.53...], "type": "Point"}'

gj = geojson.loads(dump)  # doctest: +ELLIPSIS
#{"coordinates": [43.2..., -1.53...], "type": "Point"}
pprint(gj)

{"coordinates": [43.24, -1.532], "type": "Point"}
'{"coordinates": [43.24, -1.532], "type": "Point"}'
{"coordinates": [43.24, -1.532], "type": "Point"}

Custom classes

This encoding/decoding functionality shown in the previous can be extended to custom classes using the interface described by the geo_interface Specification.

In [24]:

import geojson

class MyPoint():
     def __init__(self, x, y):
         self.x = x
         self.y = y

     @property
     def __geo_interface__(self):
         return {'type': 'Point', 'coordinates': (self.x, self.y)}

point_instance = MyPoint(52.235, -19.234)

geojson.dumps(point_instance, sort_keys=True)  # doctest: +ELLIPSIS
#'{"coordinates": [52.23..., -19.23...], "type": "Point"}'

Out[24]:

'{"coordinates": [52.235, -19.234], "type": "Point"}'

Helpful utilities

coords

geojson.utils.coords yields all coordinate tuples from a geometry or feature object.

In [27]:

import geojson

my_line = LineString([(-152.62, 51.21), (5.21, 10.69)])

my_feature = geojson.Feature(geometry=my_line)

list(geojson.utils.coords(my_feature))  # doctest: +ELLIPSIS
#[(-152.62..., 51.21...), (5.21..., 10.69...)]

Out[27]:

[(-152.62, 51.21), (5.21, 10.69)]

map_coords

geojson.utils.map_coords maps a function over all coordinate tuples and returns a geometry of the same type. Useful for translating a geometry in space or flipping coordinate order.

In [28]:

import geojson

new_point = geojson.utils.map_coords(lambda x: x/2, geojson.Point((-115.81, 37.24)))

geojson.dumps(new_point, sort_keys=True)  # doctest: +ELLIPSIS
#'{"coordinates": [-57.905..., 18.62...], "type": "Point"}'

Out[28]:

'{"coordinates": [-57.905, 18.62], "type": "Point"}'

validation

geojson.is_valid provides validation of GeoJSON objects.

In [29]:

import geojson

validation = geojson.is_valid(geojson.Point((-3.68,40.41,25.14)))
print(validation['valid'])
#'no'

print(validation['message'])
#'the "coordinates" member must be a single position'

no
the "coordinates" member must be a single position

generate_random

geojson.utils.generate_random yields a geometry type with random data

In [30]:

import geojson

geojson.utils.generate_random("LineString")  # doctest: +ELLIPSIS
#{"coordinates": [...], "type": "LineString"}

Out[30]:

{"coordinates": [[-4.454240116119678, -85.11096594745686], [-102.67726268531537, -21.1641373701423], [-175.4525855417237, 53.518811905348855]], "type": "LineString"}

Development

To build this project, run python setup.py build. To run the unit tests, run python setup.py test.

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