topic Re: How to convert m*m correlation matrix into pair-wise dataset?! in SAS Programming

How to convert m*m correlation matrix into pair-wise dataset?!

hellohere — Thu, 17 Mar 2022 10:00:11 GMT

Proc CORR creates m*m correlation matrix ... how to convert it into pair-wise dataset?!

Say here are ten variables, CORR creates 10*10 correlation matrix, need to convert into 10*10=100 row (var1 var2 corr12)..

Re: How to convert m*m correlation matrix into pair-wise dataset?!

hellohere — Thu, 17 Mar 2022 10:07:37 GMT

There way to do in R. How to do in SAS?! https://stackoverflow.com/questions/33781147/r-converting-correlation-matrix-to-pairwise

Re: How to convert m*m correlation matrix into pair-wise dataset?!

PaigeMiller — Thu, 17 Mar 2022 10:15:40 GMT

https://communities.sas.com/t5/SAS-Programming/creating-a-table-of-highly-correlated-values/m-p/802045#M315701

Re: How to convert m*m correlation matrix into pair-wise dataset?!

Rick_SAS — Thu, 17 Mar 2022 10:23:01 GMT

See the article, "Use a bar chart to visualize pairwise correlations."

The focus of that article is to create a bar chart of the pairwise correlations, but you can use the same code to create a list.

The SAS/IML language has similarities with R, but if you are new to SAS, here is an explicit example, modified from the article:


ods exclude all;
proc corr data=sashelp.Heart;      /* pairwise correlation */
   var _NUMERIC_;
   ods output PearsonCorr = Corr;  /* write correlations, p-values, and sample sizes to data set */
run;
ods exclude none;

proc iml;
use Corr;
   read all var "Variable" into ColNames;  /* get names of variables */
   read all var (ColNames) into mCorr;     /* matrix of correlations */
close Corr;

numCols = ncol(mCorr);                /* number of variables */
numPairs = numCols*(numCols-1) / 2;
length = 2*nleng(ColNames) + 5;       /* max length of new ID variable */
PairNames = j(NumPairs, 1, BlankStr(length));
i = 1;
do row= 2 to numCols;                 /* construct the pairwise names */
   do col = 1 to row-1;
      PairNames[i] = strip(ColNames[col]) + " vs. " + strip(ColNames[row]);
      i = i + 1;
   end;
end;
 
lowerIdx = loc(row(mCorr) > col(mCorr));  /* indices of lower-triangular elements */
Corr = mCorr[ lowerIdx ];

create CorrPairs var {"PairNames" "Corr"};
append;
close;
QUIT;

proc print data=CorrPairs; run;

Re: How to convert m*m correlation matrix into pair-wise dataset?!

Ksharp — Thu, 17 Mar 2022 13:25:45 GMT

data have;
 set sashelp.Heart;
run;

ods exclude all;
proc corr data=have;      /* pairwise correlation */
   var _NUMERIC_;
   ods output PearsonCorr = Corr;  /* write correlations, p-values, and sample sizes to data set */
run;
ods exclude none;

proc sort data=corr(drop=Label) out=corr2;
by variable;
run;

proc sql noprint;
select variable into : vname separated by ' ' from corr2;
quit;
proc transpose data=corr2 out=want;
by variable;
var &vname.;
run;

Re: How to convert m*m correlation matrix into pair-wise dataset?!

Tom — Thu, 17 Mar 2022 15:12:49 GMT

Why not just use normal SAS code?
Generate the correlations.

Transpose.

proc corr data=sashelp.heart out=corr noprint;
 var _numeric_;
run;
proc transpose
  data=corr(rename=(_name_=LEFT))
  out=pairs(rename=(_name_=RIGHT) drop=_label_ )
;
  by left notsorted;
  where _type_='CORR';
  id _type_;
run;

Results:

Obs    LEFT          RIGHT            CORR

  1    AgeCHDdiag    AgeCHDdiag      1.00000
  2    AgeCHDdiag    AgeAtStart      0.55091
  3    AgeCHDdiag    Height         -0.21042
  4    AgeCHDdiag    Weight         -0.13741
  5    AgeCHDdiag    Diastolic      -0.03510
  6    AgeCHDdiag    Systolic        0.06924
  7    AgeCHDdiag    MRW             0.00642
  8    AgeCHDdiag    Smoking        -0.28357
  9    AgeCHDdiag    AgeAtDeath      0.74811
 10    AgeCHDdiag    Cholesterol     0.00363
 11    AgeAtStart    AgeCHDdiag      0.55091
 12    AgeAtStart    AgeAtStart      1.00000
 13    AgeAtStart    Height         -0.13173
 14    AgeAtStart    Weight          0.09352
 15    AgeAtStart    Diastolic       0.27540
 16    AgeAtStart    Systolic        0.37938
 17    AgeAtStart    MRW             0.20451
 18    AgeAtStart    Smoking        -0.16743
 19    AgeAtStart    AgeAtDeath      0.68860
 20    AgeAtStart    Cholesterol     0.27341
 21    Height        AgeCHDdiag     -0.21042
...

You could eliminate the self correlations and the duplicate entries by just filtering to the observations where LEFT < RIGHT.

Re: How to convert m*m correlation matrix into pair-wise dataset?!

hellohere — Thu, 17 Mar 2022 22:50:49 GMT

Works great. Thanks.

Re: How to convert m*m correlation matrix into pair-wise dataset?!

hellohere — Thu, 17 Mar 2022 22:51:07 GMT

Works great. Thanks.