conditional assignment
On Mon, 26 Jan 2004 20:15:51 +0100, <uaca at alumni.uv.es> wrote:
I want to conditionally operate on certain elements of a matrix, let me explain it with a simple vector example
z<- c(1, 2, 3) zz <- c(0,0,0) null <- (z > 2) & ( zz <- z) zz
[1] 1 2 3 why zz is not (0, 0, 3) ?????
<snip>
in the other hand, it curious that null has reasonable values
null
[1] FALSE FALSE TRUE
What you have done there is create a boolean vector, null, of the same length as z (and zz). For instance: (z > 2) & (zz <- z) =(F F T) & (T T T) (as assignment - presumably - returns T) =(F F T). What will work is: z <- c(1, 2, 3) index <- z>2 zz <- z * index
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