Substitute for "For" Loop in R

Asked Nov 03 '15 at 07:10

Active Nov 03 '15 at 07:12

Viewed 139 times

I am aware that a for-loop isn't the best thing to use in R. Please suggest an alternative to the snippet below:

mat is a 2-D matrix pos.scores and neg.scores are 1-D matrices

I am trying to populate the pos.scores and neg.scores matrices using some computation (if-else statements).

for (i in 1:(ncol(mat)-1)) 
{
pos.scores[1,i]<-ifelse(sum(mat[,i]>0 & mat[,ncol(mat)]=="Positive")==0,0.000001,sum(mat[,i]>0 & mat[,ncol(mat)]=="Positive"))/nrow(mat)    
neg.scores[1,i]<-ifelse(sum(mat[,i]>0 & mat[,ncol(mat)]=="Negative")==0,0.000001,sum(mat[,i]>0 & mat[,ncol(mat)]=="Negative"))/nrow(mat)        
}

edited Nov 03 '15 at 07:12

Jaap

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asked Nov 03 '15 at 07:10

Santhosh Krishnan R

Please show a small reproducible example and expected output based on that. – akrun Nov 03 '15 at 07:12
[More info on how to give a reproducible example](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example/5963610) – Jaap Nov 03 '15 at 07:12
2

Try `colSums(mat[,-ncol(mat)]>0 & mat[, ncol(mat)]=='Positive')` instead – akrun Nov 03 '15 at 07:13
Thanks - this works! – Santhosh Krishnan R Nov 03 '15 at 07:58

Substitute for "For" Loop in R

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