*! version 1.0.0 15mar2010
help spmat summarize

Title

spmat summarize -- Summarize the spatial-weighting
matrix W contained in an spmat object

Syntax

spmat summarize objname [, options]

links report links

detail display detailed summary of links

banded display banded information

btruncate(b B) bin truncation

dtruncate(l u) diagonal truncation

vtruncate(#) value truncation

Only one of banded, btruncate(), dtruncate(), or
vtruncate() may be specified.

Description

spmat summarize summarizes the spatial-weighting
matrix W contained in the spmat object objname.
If the object contains an n x n matrix, the user can optionally
request summary statistics that show whether the matrix can be
stored in a banded form.

Options

links requests that spmat summarize reports links rather than the
default values. This option is useful for summarizing contiguity matrices.

detail requests a detailed tabulation of links.
detail will also display IDs of observations with the minimum and
maximum number of links.

banded reports the bands for the matrix that has already a (possibly)
banded structure but is stored in an n x n form.

truncate() options report the bands for the matrix after its values have
been changed to zero according to one of the truncation criterion.

btruncate(b B) partitions the values of W into
B bins and truncates to zero those entries that fall
into bin b or below.

dtruncate(l u) truncates to zero the values of W
that fall l diagonals below and u diagonals
above the main diagonal. Neither value can be greater
than floor((cols(W)-1)/4).

vtruncate(#) truncates to zero the values of W
that are less than or equal to #.

Example

Setup

. spmat use cobj using pollute.spmat

Summarize the contiguity matrix contained in the spmat object cobj

. spmat summarize cobj, links

Saved results

spmat summarize saves the following in r():

Scalars

r(b) number of rows in W

r(n) number of columns in W

r(lband) lower band of W

r(uband) upper band of W

r(min) minimum of W

r(min0) minimum element > 0 in W

r(mean) mean of W

r(max) maximum of W

r(lmin) minimum number of neighbors in W

r(lmean) mean number of neighbors in W

r(lmax) maximum number of neighbors in W

r(ltotal) total number of neighbors in W

r(eig) 1 if object contains eigenvalues, 0 otherwise

r(canband) 1 if W can be banded based on r(lband)
and r(uband), 0 otherwise

Also see

Online: spmat, spreg, spivreg,
spmap, shp2dta, mif2dta (if installed)