Compute matrix based on logical expression

Asked Mar 19 '15 at 15:47

Active Mar 19 '15 at 15:47

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I need to compute a matrix base on a logical expression.

I have a matrix called A and a matrix called B:

A=matrix(c(1,1,1,1),nrow=2,ncol=2)
B=matrix(c(2,2,2,2),nrow=2,ncol=2)

Based on whether a variable called lambda is equal to one, I want to compute a matrix C, which is equal to A. On the other hand, if lambda is equal to zero, the matrix C should be equal to the matrix B. It should look something like this, but it doesn't seem to work:

C=ifelse(lambda==1,A,B)

Thanks.

asked Mar 19 '15 at 15:47

Ku-trala

2

`if(lambda == 1) A else B`. – user20650 Mar 19 '15 at 15:51
2

`C <- (lambda==1)*A + (lambda!=1)*B` – Khashaa Mar 19 '15 at 15:52
2

This is a case for `if(){}else{}`, namely : `C=if( lambda==1 ){ A }else{ B }` – IRTFM Mar 19 '15 at 15:52
1

Read the paragraph labeled "Warning" in the help page for "ifelse" – Rick Mar 19 '15 at 15:57

Compute matrix based on logical expression

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