skip to navigation
skip to content

Not Logged In

pygeoif 0.4.1

A basic implementation of the __geo_interface__

Introduction

PyGeoIf provides a GeoJSON-like protocol for geo-spatial (GIS) vector data.

see https://gist.github.com/2217756

Other Python programs and packages that you may have heard of already implement this protocol:

So when you want to write your own geospatilal library with support for this protocol you may use pygeoif as a starting point and build your functionality on top of it

You may think of pygeoif as a 'shapely ultralight' which lets you construct geometries and perform very basic operations like reading and writing geometries from/to WKT, constructing line strings out of points, polygons from linear rings, multi polygons from polygons, etc. It was inspired by shapely and implements the geometries in a way that when you are familiar with shapely you feel right at home with pygeoif

It was written to provide clean and python only geometries for fastkml

PyGeoIf is continually tested with Travis CI

https://api.travis-ci.org/cleder/pygeoif.png https://coveralls.io/repos/cleder/pygeoif/badge.png?branch=master

Example

>>> from pygeoif import geometry
>>> p = geometry.Point(1,1)
>>> p.__geo_interface__
{'type': 'Point', 'coordinates': (1.0, 1.0)}
>>> print p
POINT (1.0 1.0)
>>> p1 = geometry.Point(0,0)
>>> l = geometry.LineString([p,p1])
>>> l.bounds
(0.0, 0.0, 1.0, 1.0)
>>> dir(l)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__',
'__geo_interface__', '__getattribute__', '__hash__', '__init__',
'__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__',
'__setattr__', '__sizeof__', '__str__', '__subclasshook__',
'__weakref__', '_coordinates', '_geoms', '_type', 'bounds', 'coords',
'geom_type', 'geoms', 'to_wkt']
>>> print l
LINESTRING (1.0 1.0, 0.0 0.0)

You find more examples in the tests.py file which cover every aspect of pygeoif or in fastkml.

Classes

All classes implement the attributes:

  • __geo_interface__: as dicussed above
  • geom_type: Returns a string specifying the Geometry Type of the object
  • bounds: Returns a (minx, miny, maxx, maxy) tuple (float values) that bounds the object.
  • wkt: Returns the 'Well Known Text' representation of the object

and the method:

  • to_wkt which also prints the object

Point

A zero dimensional feature

Attributes

x, y, z : float
Coordinate values

Example

>>> p = Point(1.0, -1.0)
>>> print p
POINT (1.0000000000000000 -1.0000000000000000)
>>> p.y
-1.0
>>> p.x
1.0

LineString

A one-dimensional figure comprising one or more line segments

A LineString has non-zero length and zero area. It may approximate a curve and need not be straight. Unlike a LinearRing, a LineString is not closed.

Attributes

geoms : sequence
A sequence of Points

LinearRing

A closed one-dimensional feature comprising one or more line segments

A LinearRing that crosses itself or touches itself at a single point is invalid and operations on it may fail.

A Linear Ring is self closing

Polygon

A two-dimensional figure bounded by a linear ring

A polygon has a non-zero area. It may have one or more negative-space "holes" which are also bounded by linear rings. If any rings cross each other, the feature is invalid and operations on it may fail.

Attributes

exterior : LinearRing
The ring which bounds the positive space of the polygon.
interiors : sequence
A sequence of rings which bound all existing holes.

MultiPoint

A collection of one or more points

Attributes

geoms : sequence
A sequence of Points

MultiLineString

A collection of one or more line strings

A MultiLineString has non-zero length and zero area.

Attributes

geoms : sequence
A sequence of LineStrings

MultiPolygon

A collection of one or more polygons

Attributes

geoms : sequence
A sequence of Polygon instances

GeometryCollection

A heterogenous collection of geometries (Points, LineStrings, LinearRings and Polygons, MultiPoints, MultiLineStrings, MultiPolygons)

Attributes

geoms : sequence
A sequence of geometry instances

Please note: GEOMETRYCOLLECTION isn't supported by the Shapefile format. And this sub-class isn't generally supported by ordinary GIS sw (viewers and so on). So it's very rarely used in the real GIS professional world.

Functions

as_shape

Create a pygeoif feature from an object that provides the __geo_interface__

>>> from shapely.geometry import Point
>>> from pygeoif import geometry
>>> geometry.as_shape(Point(0,0))
<pygeoif.geometry.Point object at 0x...>

from_wkt

Create a geometry from its WKT representation

>>> p = geometry.from_wkt('POINT (0 1)')
>>> print p
POINT (0.0 1.0)

signed_area

Return the signed area enclosed by a ring using the linear time algorithm at http://www.cgafaq.info/wiki/Polygon_Area. A value >= 0 indicates a counter-clockwise oriented ring.

orient

Returns a copy of the polygon with exterior in counter-clockwise and interiors in clockwise orientation for sign=1.0 and the other way round for sign=-1.0

mapping

Returns the __geo_interface__ dictionary

Changelog

0.4.1 (2013/10/25)

  • GeometryCollections return tuples as the __geo_interface__
  • A GeometryCollection can contain MultiGeometries

0.4 (2013/10/25)

  • after a year in production promote it to Development Status :: 5 - Production/Stable
  • MultiPolygons return tuples as the __geo_interface__

0.3.1 (2012/11/15)

  • specify minor python versions tested with Travis CI
  • fix for signed area

0.3 (2012/11/14)

  • add GeometryCollection
  • len(Multi*) and len(GeometryCollection) returns the number of contained Geometries
  • add orient function to get clockwise or counterclockwise oriented poygons
  • add signed_area function
  • add _set_orientation method to lineStrings, Polygons and MultiPolygons

0.2.1 (2012/08/02)

  • as_shape also accepts an object that is neither a dictionary nor has a __geo_interface__ but can be converted into a __geo_interface__ compliant dictionary

0.2 (2012/08/01)

  • change license to LGPL
  • add wkt as a property
  • as_shape also accepts a __geo_interface__ compliant dictionary
  • test with python3

0.1 (2012/07/27)

  • initial release
 
File Type Py Version Uploaded on Size
pygeoif-0.4.1.tar.gz (md5) Source 2013-10-25 27KB
  • Downloads (All Versions):
  • 29 downloads in the last day
  • 149 downloads in the last week
  • 841 downloads in the last month