On Jun 28, 2012, at 9:18 PM, lynx wrote:
I have a dataset named DM with p1, p2, ...., p9 (9 columns,
numerical values)
I would like to calculate to multify each pair of columns (p1p2,
p1p3,...
p1p9, p2p3, p2p4.... p8p9) and assign them in p1p2, p1p3,... p1p9,
p2p3,
p2p4.... p8p9
In SAS,
l=0;
p_int_sum=0;
do i=1 to 8;
do j=(i+1) to 9;
l=l+1;
p{i}p{j}=p{i}*p{j};
end;
end;
I would like to know how to assign them in R
I tried for function but failed.
for (i in 1:8) {
for (j in 2:9) {
# Try instead:
DM[[ paste("p",i, "p",j,sep="") ]] <-
DM[[paste("p",i, sep="")]] * DM[[paste("p",i, sep="")]]
DM$p[i]p[j] <- DM$p[i] * DM$p[j]
}}
I suspect there is a more elegant method than this use of R as a macro
processor. I tested the above approach with suitably smalled
subscripts on a smaller dataset:
DM <- data.frame(p1=1:10,p2=1:10,p3=1:10,p4=1:10,p5=1:10)
--
David Winsemius, MD
West Hartford, CT
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