*! version 1.0.1 16mar2010
help spmat import

Title

spmat import -- Create an spmat object from a
text file

Syntax

spmat import objname using filename
[, options]

noid filename does not contain unique IDs

nlist filename contains a neighbor list

geoda filename was created by the GeoDa (TM) software

idistance convert distance data to inverse distances

normalize(norm) normalization method

replace replace objname

Description

spmat import creates the spmat object objname from the text
file filename.

By default, spmat import imports data from a space-delimited text file
in which the first line contains the number of columns of the spatial-weighting
matrix and, if applicable, the lower and upper band, followed by the matrix
stored row-by-row with unique place identifiers recorded in the first
column.

Options

noid alerts spmat import that filename does not
contain unique place identifiers. If so, Stata will create
IDs 1, ..., n.

nlist specifies that the text file is in the neighbor-list format.
The first line of the file must contain the total number
of places and, if the matrix is banded, the lower and upper band.
Each remaining line lists a place ID followed by its neighbors, if any.

geoda specifes that filename is in the .gwt or .gal
format created by the GeoDa (TM) software.

idistance tells spmat that the data be converted to inverse
distances. The value d will be converted to 1/d with the exception
of the main diagonal, which will contain zero entries.

normalize(norm) specifies the normalization method.
norm can be row, minmax, or spectral.

replace allows objname to be overwritten if it already exists.

Example

Setup

. clear all

. set memory 50m

. use pollute

. spmat contiguity cobj using pollutexy, id(id) normalize(minmax)

. spmat export cobj using cobj.txt

. spmat drop cobj

Create the spmat object cobj from the file cobj.txt

. spmat import cobj using cobj.txt

Also see

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