help spmat summarize
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Title

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


Syntax

        spmat summarize objname [, options]

    options                       Description
    -------------------------------------------------------------------------
      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)