st: example spwm2.ado

[Danielle Deemer <deemer.7@buckeyemail.osu.edu>]

Hello - 

I'm trying to create a spatial weight matrix for county-level data using -spatwmat- for a data set containing 2962 observations (i.e., counties).

[-spatwmat- is from STB-60 and available via -findit-.]

I am using State 12 SE for windows (64-bit), but am running out of memory (max 8g). So, I found the code for the -spwm2.ado- in Statalist archives (info/code below).

I am not very familiar with loops and am new to spatial commands. I am wondering if anyone has used this spwm2.ado file and would be willing to share it as an example, so that I can figure out how to adapt the .ado file for my command: 

spatwmat, name(ws) xcoord(latitude) ycoord(longitude) band(0 1) bin

Thank you in advance!

Dani Deemer

Here is the spwm2.ado info/code:

*! -spwm2- 1.0 - 30 Nov 2010 austinnichols@gmail.com posted to Statalist
 * based on
 * Version 1.0 - 29 January 2001 STB-60 sg162
 * -spatwmat- Generates different kinds of spatial weights matrices
 * Author: Maurizio Pisati
 * Department of Sociology and Social Research
 * University of Milano Bicocca (Italy)
 * maurizio.pisati@galactica.it
 prog spwm2
 version 9.2
 syntax [using/], Name(string)                           /*
           */     [DROP(numlist min=1 =0 sort)]         /*
           */     [Xcoord(varname numeric)]              /*
           */     [Ycoord(varname numeric)]              /*
           */     [Band(numlist min=2 max=2 =0 sort)]   /*
           */     [Friction(real 1)]                     /*
           */     [BINary]                               /*
           */     [Standardize]                          /*
           */     [Eigenval(string)]
 confirm name `name'
 tempname D W V L R
 if "`using'"=="" & ("`xcoord'"=="" | "`ycoord'"=="") {
  di as err "You must specify both x- and y-coordinates using options "
  di as err "{bf:{ul:x}coord({it:varname})} and " _c
  di as err "{bf:{ul:y}coord({it:varname})}"
  exit
 }
 if "`using'"=="" & "`band'"=="" {
     di as err "You must specify distance band using option " _c
     di as err "{bf:{ul:b}and({it:numlist})}"
     exit
 }
 local OUTPUT "The following matrix has been created:"
 if "`using'"!="" {
  preserve
  qui use `"`using'"', clear
  /* Drop rows and columns if requested */
     if "`drop'"!="" {
         local NDROP : word count `drop'
         unab VLIST : _all
         qui generate RDROP=0
         local i=1
         while `i'<=`NDROP' {
             local D : word `i' of `drop'
             local VAR : word `D' of `VLIST'
          local CDLIST "`CDLIST'`VAR' "
          qui replace RDROP=1 in `D'
             local i=`i'+1
         }
         qui drop `CDLIST'
         qui drop if RDROP
         qui drop RDROP
     }
  /* Check if weights are binary */
     unab VLIST : _all
     local NVAR : word count `VLIST'
     local SUM=0
     local i=1
     while `i'<=`NVAR' {
         local VAR : word `i' of `VLIST'
         qui capture assert `VAR'==0 | `VAR'==1
        if _rc!=0 {
            local SUM=`SUM'+1
        }
         local i=`i'+1
     }
     if `SUM'==0 {
         local binary "binary"
     }
     else {
         local binary ""
     }
  /* Check if each location has at least one neighbor */
     qui egen ROWSUM=rsum(_all)
     qui count if ROWSUM==0
     local NN=r(N)
     qui drop ROWSUM
  /* Create intermediate matrix `W' */
    qui mkmat _all, matrix(`W')
    restore
  /* Check if matrix is square*/
    local NROW=rowsof(`W')
    local NCOL=colsof(`W')
    if `NROW'!=`NCOL' {
    	di as err "Matrix is not square"
    	exit
    }
    local N=`NROW'
  /* Create labels */
    if "`binary'"!="" {
    	local WT "Imported binary weights matrix"
    }
    else {
    	local WT "Imported non-binary weights matrix"
    }
  /* Create final matrix */
    matrix `name'=`W'
 }
 *********
 *  5. Create distance-based weights matrix
 *********
 if `"`using'"'=="" {
  /* Define distance band */
  local LOWER : word 1 of `band'
  local UPPER : word 2 of `band'
  /* Check appropriateness of coordinate variables */
  capture qui assert `xcoord'!=.
  if _rc!=0 {
   di as err "Variable `xcoord' has missing values"
   exit
   }
  capture qui assert `ycoord'!=.
  if _rc!=0 {
   di as err "Variable `ycoord' has missing values"
   exit
   }
  local N=_N
  /* Create intermediate matrix */
   matrix `W'=J(`N',`N',0)
   matrix `D'=J(`N',`N',0)
   local MAXOBS=(`N'/2)*(`N'-1)
   local d=1
   local i=1
   while `i'<=`N' {
         local j=`i'+1
         while `j'<=`N' {
             local A=(`xcoord'[`i']-`xcoord'[`j'])^2
             local B=(`ycoord'[`i']-`ycoord'[`j'])^2
             local DIST=sqrt(`A'+`B')
             matrix `D'[`i',`j']=`DIST'
             matrix `D'[`j',`i']=`DIST'
             if `DIST'`LOWER' & `DIST'<=`UPPER' {
                 if "`binary'"!="" {
                     matrix `W'[`i',`j']=1
                     matrix `W'[`j',`i']=1
                 }
                 else {
                     matrix `W'[`i',`j']=1/(`DIST'^`friction')
                     matrix `W'[`j',`i']=1/(`DIST'^`friction')
                 }
             }
            local d=`d'+1
            local j=`j'+1
         }
        local i=`i'+1
     }
 mata:`W'=st_matrix("`W'")
 mata:`D'=st_matrix("`D'")
     /* Generate distance statistics */
 mata:st_local("MAXMIN",strofreal(colmin(rowmax(`D'))))
 mata:st_local("MINMAX",strofreal(colmax(rowmin(`D'))))
     /* Check if each location has at least one neighbor */
 mata:st_local("NN",strofreal(colsum(rowsum(`W'):==0)))
 
    /* Create labels */
    if "`binary'"!="" {
    	local WT "Distance-based binary weights matrix"
    }
    else {
    	local WT "Inverse distance weights matrix"
    }
 
    /* Create final matrix */
    matrix `name'=`W'
 }
 *********
 *  6. Row-standardize weights matrix
 *********
 if "`standardize'"!="" {
 mata:st_matrix("`W'",`W':/(rowsum(`W')+(rowsum(`W'):==0)))
  }
 *********
 *  7. Create weights matrix eigenvalues
 *********
 if "`eigenval'"!="" & `NN'0 {
     di as err "Eigenvalues matrix cannot be computed because of the  presence"
     di as err "of one or more locations with no neighbors"
 }
 if "`eigenval'"!="" & `NN'==0 {
 mata:`L'=.
 mata:`V'=.
 mata:`R'=diag(rowsum(`W'):^(-1/2))
 mata:eigensystem(`R'*`W'*`R',`V',`L')
 mata:st_matrix("`eigenval'",sort(Re(`L''),-1))
    local OUTPUT "The following matrices have been created:"
    matrix `name'=`W'
    }
 *********
 *  8. Add relevant info to weights matrix
 *********
 if "`using'"!="" & "`binary'"!="" local ROW="SWMImpo Yes "
 if "`using'"!="" & "`binary'"=="" local ROW="SWMImpo No  "
 if "`using'"=="" & "`binary'"!="" local ROW="SWMDist Yes "
 if "`using'"=="" & "`binary'"=="" local ROW="SWMDist No  "
 if "`standardize'"!="" {
     local ROW="`ROW'Yes"
 }
 else {
     local ROW="`ROW'No"
 }
 matrix rownames `name'=`ROW'
 if "`using'"=="" {
    local INT=int(`LOWER')
    local DEC=`LOWER'-`INT'
    local DEC=string(`DEC')
    local COL "`INT' `DEC'"
    local INT=int(`UPPER')
    local DEC=`UPPER'-`INT'
    local DEC=string(`DEC')
    local COL "`COL' `INT' `DEC'"
    matrix colnames `name'=`COL'
 }
 *********
 *  9. Display report
 *********
 if "`standardize'"!="" {
    local S "(row-standardized)"
 }
 di _newline
 di as txt "`OUTPUT'"
 di ""
 di as txt "1. `WT' " as res "`name'" as txt " `S'"
 di as txt "   Dimension: " as res "`N'x`N'"
 if "`using'"=="" {
  di as txt "   Distance band: " as res "`LOWER' < d <= `UPPER'"
  di as txt "   Friction parameter: " as res "`friction'"
  di as txt "   Largest minimum distance: " %-9.2f as res `MAXMIN'
  di as txt "   Smallest maximum distance: " %-9.2f as res `MINMAX'
 }
 if `NN'==1 {
     di ""
     di as err "   Beware! `NN' location has no neighbors"
 }
 else if `NN'1 {
     di ""
     di as err "   Beware! `NN' locations have no neighbors"
 }
 if `NN'0 & "`using'"=="" {
     di as err "   You are advised to extend the distance band"
 }
 if "`eigenval'"!="" & `NN'==0 {
    di ""
     di as txt "2. Eigenvalues matrix " as res "`eigenval'"
     di as txt "   Dimension: " as res "`N'x1"
 }
 di _newline
 *********
 *  10. End program
 *********
 capture matrix drop `W'
 capture matrix drop `W'S
 end



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