Measurement

pygeos.measurement.area(geometry, **kwargs)

Computes the area of a (multi)polygon.

Parameters

geometryGeometry or array_like

Examples

>>> area(Geometry("POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))"))
100.0
>>> area(Geometry("MULTIPOLYGON (((0 0, 0 10, 10 10, 0 0)), ((0 0, 0 10, 10 10, 0 0)))"))
100.0
>>> area(Geometry("POLYGON EMPTY"))
0.0
>>> area(None)
nan

pygeos.measurement.bounds(geometry, **kwargs)

Computes the bounds (extent) of a geometry.

For each geometry these 4 numbers are returned: min x, min y, max x, max y.

Parameters

geometryGeometry or array_like

Examples

>>> bounds(Geometry("POINT (2 3)")).tolist()
[2.0, 3.0, 2.0, 3.0]
>>> bounds(Geometry("LINESTRING (0 0, 0 2, 3 2)")).tolist()
[0.0, 0.0, 3.0, 2.0]
>>> bounds(Geometry("POLYGON EMPTY")).tolist()
[nan, nan, nan, nan]
>>> bounds(None).tolist()
[nan, nan, nan, nan]

pygeos.measurement.distance(a, b, **kwargs)

Computes the Cartesian distance between two geometries.

Parameters

a, bGeometry or array_like

Examples

>>> point = Geometry("POINT (0 0)")
>>> distance(Geometry("POINT (10 0)"), point)
10.0
>>> distance(Geometry("LINESTRING (1 1, 1 -1)"), point)
1.0
>>> distance(Geometry("POLYGON ((3 0, 5 0, 5 5, 3 5, 3 0))"), point)
3.0
>>> distance(Geometry("POINT EMPTY"), point)
nan
>>> distance(None, point)
nan

pygeos.measurement.frechet_distance(a, b, densify=None, **kwargs)

Compute the discrete Fréchet distance between two geometries.

The Fréchet distance is a measure of similarity: it is the greatest distance between any point in A and the closest point in B. The discrete distance is an approximation of this metric: only vertices are considered. The parameter ‘densify’ makes this approximation less coarse by splitting the line segments between vertices before computing the distance.

Fréchet distance sweep continuously along their respective curves and the direction of curves is significant. This makes it a better measure of similarity than Hausdorff distance for curve or surface matching.

Parameters

a, bGeometry or array_like

densifyfloat, array_like or None

The value of densify is required to be between 0 and 1.

Examples

>>> line_1 = Geometry("LINESTRING (0 0, 100 0)")
>>> line_2 = Geometry("LINESTRING (0 0, 50 50, 100 0)")
>>> frechet_distance(line_1, line_2)  
70.71...
>>> frechet_distance(line_1, line_2, densify=0.5)
50.0
>>> frechet_distance(line_1, Geometry("LINESTRING EMPTY"))
nan
>>> frechet_distance(line_1, None)
nan

pygeos.measurement.hausdorff_distance(a, b, densify=None, **kwargs)

Compute the discrete Hausdorff distance between two geometries.

The Hausdorff distance is a measure of similarity: it is the greatest distance between any point in A and the closest point in B. The discrete distance is an approximation of this metric: only vertices are considered. The parameter ‘densify’ makes this approximation less coarse by splitting the line segments between vertices before computing the distance.

Parameters

a, bGeometry or array_like

densifyfloat, array_like or None

The value of densify is required to be between 0 and 1.

Examples

>>> line_1 = Geometry("LINESTRING (130 0, 0 0, 0 150)")
>>> line_2 = Geometry("LINESTRING (10 10, 10 150, 130 10)")
>>> hausdorff_distance(line_1, line_2)  
14.14...
>>> hausdorff_distance(line_1, line_2, densify=0.5)
70.0
>>> hausdorff_distance(line_1, Geometry("LINESTRING EMPTY"))
nan
>>> hausdorff_distance(line_1, None)
nan

pygeos.measurement.length(geometry, **kwargs)

Computes the length of a (multi)linestring or polygon perimeter.

Parameters

geometryGeometry or array_like

Examples

>>> length(Geometry("LINESTRING (0 0, 0 2, 3 2)"))
5.0
>>> length(Geometry("MULTILINESTRING ((0 0, 1 0), (0 0, 1 0))"))
2.0
>>> length(Geometry("POLYGON((0 0, 0 10, 10 10, 10 0, 0 0))"))
40.0
>>> length(Geometry("LINESTRING EMPTY"))
0.0
>>> length(None)
nan

pygeos.measurement.minimum_clearance(geometry, **kwargs)

Computes the Minimum Clearance distance.

A geometry’s “minimum clearance” is the smallest distance by which a vertex of the geometry could be moved to produce an invalid geometry.

If no minimum clearance exists for a geometry (for example, a single point, or an empty geometry), infinity is returned.

Parameters

geometryGeometry or array_like

Examples

>>> minimum_clearance(Geometry("POLYGON((0 0, 0 10, 5 6, 10 10, 10 0, 5 4, 0 0))"))
2.0
>>> minimum_clearance(Geometry("POLYGON EMPTY"))
inf
>>> minimum_clearance(None)
nan

pygeos.measurement.total_bounds(geometry, **kwargs)

Computes the total bounds (extent) of the geometry.

Parameters

geometryGeometry or array_like

Returns

numpy ndarray of [xmin, ymin, xmax, ymax]

>>> total_bounds(Geometry("POINT (2 3)")).tolist()
    ..

[2.0, 3.0, 2.0, 3.0]

>>> total_bounds([Geometry("POINT (2 3)"), Geometry("POINT (4 5)")]).tolist()
    ..

[2.0, 3.0, 4.0, 5.0]

>>> total_bounds([Geometry("LINESTRING (0 1, 0 2, 3 2)"),Geometry("LINESTRING (4 4, 4 6, 6 7)")]).tolist()
    ..

[0.0, 1.0, 6.0, 7.0]

>>> total_bounds(Geometry("POLYGON EMPTY")).tolist()
    ..

[nan, nan, nan, nan]

>>> total_bounds([Geometry("POLYGON EMPTY"), Geometry("POINT (2 3)")]).tolist()
    ..

[2.0, 3.0, 2.0, 3.0]

>>> total_bounds(None).tolist()
    ..

[nan, nan, nan, nan]