libpysal.cg.PointLocator¶

class libpysal.cg.PointLocator(points)[source]¶

An abstract representation of a point indexing data structure.

Create a point locator for a sequence of points.

Parameters:¶

points : list¶: A list of points to index.

Examples

>>> points = [Point((0, 0)), Point((1, 6)), Point((5.4, 1.4))]
>>> pl = PointLocator(points)

Methods

`nearest`(query_point)	Returns the nearest point indexed to a query point.
`overlapping`(region_rect)	Returns the indexed points located inside a rectangular query region.
`polygon`(polygon)	Returns the indexed points located inside a polygon
`proximity`(origin, r)	Returns the indexed points located within some distance of an origin point.
`region`(region_rect)	Returns the indexed points located inside a rectangular query region.

nearest(query_point)[source]¶

Returns the nearest point indexed to a query point.

nearest(Point) -> Point

Parameters:¶

query_point : a point to find the nearest indexed point to¶

Examples

>>> points = [Point((0, 0)), Point((1, 6)), Point((5.4, 1.4))]
>>> pl = PointLocator(points)
>>> n = pl.nearest(Point((1, 1)))
>>> str(n)
'(0.0, 0.0)'

overlapping(region_rect)[source]¶

Returns the indexed points located inside a rectangular query region.

region(Rectangle) -> Point list

Parameters:¶

region_rect : the rectangular range to find indexed points in¶

Examples

>>> points = [Point((0, 0)), Point((1, 6)), Point((5.4, 1.4))]
>>> pl = PointLocator(points)
>>> pts = pl.region(Rectangle(-1, -1, 10, 10))
>>> len(pts)
3

polygon(polygon)[source]¶: Returns the indexed points located inside a polygon

proximity(origin, r)[source]¶

Returns the indexed points located within some distance of an origin point.

proximity(Point, number) -> Point list

Parameters:¶

origin : the point to find indexed points near¶
r : the maximum distance to find indexed point from the origin point¶

Examples

>>> points = [Point((0, 0)), Point((1, 6)), Point((5.4, 1.4))]
>>> pl = PointLocator(points)
>>> len(pl.proximity(Point((1, 0)), 2))
1

region(region_rect)[source]¶

Returns the indexed points located inside a rectangular query region.

region(Rectangle) -> Point list

Parameters:¶

region_rect : the rectangular range to find indexed points in¶

Examples

>>> points = [Point((0, 0)), Point((1, 6)), Point((5.4, 1.4))]
>>> pl = PointLocator(points)
>>> pts = pl.region(Rectangle(-1, -1, 10, 10))
>>> len(pts)
3