Weights for circle, spheres and other connected on borders

[ozak]

Hi, I wanted to know if there is a way of generating weights for circles, spheres and such in a way similar to

w=pysal.lat2W(3,1)?

This generates

w.full()
Out[62]: (array([[ 0.,  1.,  0.],
[ 1.,  0.,  1.],
[ 0.,  1.,  0.]]), [0, 1, 2])

But on a circle it should be

(array([[ 0.,  1.,  1.],
[ 1.,  0.,  1.],
[ 1.,  1.,  0.]]), [0, 1, 2])

Thanks!

[Algogator]

Could I get assigned to this?

[ljwolf]

Sure! This'd be a real good way to get a head around how pysal works with and thinks about spatial relationships.

[Algogator]

@ljwolf could I get some info on how that weight matrix came about?

[sjsrey]

@Algogator The lat2W function is really a helper function that defines the neighbor relations in a dictionary, and then passes that dict to the W class. So to do something similar for say, circles or spheres, one would come up with the function to define the neighbors, then use that as an argument for the constructor to get a W.

The circle case is a 1-dimensional wrapping of the row lattice to a torus. We have talked about adding a torus option to lat2w so perhaps this is something to consider?

[Algogator]

@sjsrey torus=True/False like in R?

And would that be wrapping both the rows and columns?

[sjsrey]

Yes, wrapping in both row and columns.

[aghinsa]

Is this issue solved?if not can i try working on it?

[sjsrey]

@aghinsa it is still open if you would like to work on it. A PR would be welcome.

[MgeeeeK]

@aghinsa it is still open if you would like to work on it. A PR would be welcome.

hi @sjsrey... i just wanted to know if this issue is already taken? if not then i can work upon this issue...

[MgeeeeK]

another doubt...for rook=false what will be the the expected output for the corner point such as... m = ps.lib.weights.lat2W(3,3,rook=False) m.neighbors[2] original output is [1, 5, 4]

[sjsrey]

@MgeeeeK The issue is still open and available.

For rook=False the queen definition applies. So location 2 is in the upper right corner of the lattice, 1 is to its left, 4 shares a vertex at the sw corner of cell 2, and cell 5 is directly below cell 2.

[MgeeeeK]

@MgeeeeK The issue is still open and available.

For rook=False the queen definition applies. So location 2 is in the upper right corner of the lattice, 1 is to its left, 4 shares a vertex at the sw corner of cell 2, and cell 5 is directly below cell 2.

Sorry if i was not clear before.... What i meant was...after wrapping rows and columns, what will be the upper right corner neighbor of 2