libpysal.weights.w_subset

libpysal.weights.w_subset(w1, ids, **kwargs)[source]

Returns a binary weights object, w, that includes only those observations in ids.

Parameters
w1W

object

idslist

A list containing the IDs to be include in the returned weights object.

**kwargskeyword arguments

optional arguments for pysal.weights.W

Returns
wW

object

Examples

Construct a rook weights matrix for a 6x4 region (24 areas). By default PySAL assigns integer IDs to the areas in a region. By passing in a list of integers from 0 to 15, the first 16 areas are extracted from the previous weights matrix, and only those joins relevant to the new region are retained.

>>> from libpysal.weights import lat2W, w_subset
>>> w1 = lat2W(6,4)
>>> ids = range(16)
>>> w = w_subset(w1, ids)
>>> w1[0] == w[0]
True
>>> w1.neighbors[15]
[11, 14, 19]
>>> w.neighbors[15]
[11, 14]