pyguymer3.geo.buffer

pyguymer3.geo.buffer(shape, dist, /, *, debug=True, eps=1e-12, fill=1.0, fillSpace='EuclideanSpace', keepInteriors=True, nAng=9, nIter=100, prefix='.', ramLimit=1073741824, simp=0.1, tol=1e-10)[source]

Buffer a shape

This function reads in a shape that exists on the surface of the Earth and returns the same shape buffered by a constant distance (in metres).

Parameters:

  • shape (shapely.coords.CoordinateSequence, shapely.geometry.point.Point, shapely.geometry.multipoint.MultiPoint, shapely.geometry.polygon.LinearRing, shapely.geometry.linestring.LineString, shapely.geometry.multilinestring.MultiLineString, shapely.geometry.polygon.Polygon, shapely.geometry.multipolygon.MultiPolygon) – the shape

  • dist (float) – the Geodesic distance to buffer each point within the shape by (in metres)

  • debug (bool, optional) – print debug messages

  • eps (float, optional) – the tolerance of the Vincenty formula iterations

  • fill (float, optional) – the Euclidean or Geodesic distance to fill in between each point within the shapes by (in degrees or metres)

  • fillSpace (str, optional) – the geometric space to perform the filling in (either “EuclideanSpace” or “GeodesicSpace”)

  • keepInteriors (bool, optional) – keep the interiors of the Polygon

  • nAng (int, optional) – the number of angles around each point within the shape that are calculated when buffering

  • nIter (int, optional) – the maximum number of iterations (particularly the Vincenty formula)

  • prefix (str, optional) – change the name of the output debugging CSVs

  • ramLimit (int, optional) – the maximum RAM usage of each “large” array (in bytes)

  • simp (float, optional) – how much intermediary [Multi]Polygons are simplified by; negative values disable simplification (in degrees)

  • tol (float, optional) – the Euclidean distance that defines two points as being the same (in degrees)

Returns:

buff – the buffered shape

Return type:

shapely.geometry.polygon.Polygon, shapely.geometry.multipolygon.MultiPolygon

Notes

According to the Shapely documentation for the method object.buffer() :

“Passed a distance of 0, buffer() can sometimes be used to “clean” self-touching or self-crossing polygons such as the classic “bowtie”. Users have reported that very small distance values sometimes produce cleaner results than 0. Your mileage may vary when cleaning surfaces.”

According to the Shapely documentation for the function shapely.geometry.polygon.orient() :

“A sign of 1.0 means that the coordinates of the product’s exterior ring will be oriented counter-clockwise.”

Copyright 2017 Thomas Guymer [1]

References