# [R] R vector

Tue Jun 11 17:05:41 CEST 2013

```Hello,

You can write your own function, allowing for a condition argument.

rowMeansCond <- function(x, cond = ">", na.rm= FALSE){
rowm <- function(x, cond = ">", na.rm = FALSE){
f <- function(x){
eval(parse(text = paste("x", cond, "0")))
}
if(na.rm) x <- x[!is.na(x)]
i <- f(x)
if(any(i)) mean(x[i]) else NA
}
apply(x, 1, rowm, cond, na.rm)
}

x1 <- c(1, 1, -1, -1)
x2 <- -2:1
rowMeansCond(cbind(x1, x2))  # note the NA, no values are positive
rowMeansCond(cbind(x1, x2), cond = "<")

Hope this helps,

Em 11-06-2013 13:18, felice escreveu:
> hello,
>
> when i use the function rowMeans, which is sum/n, can i divide it in 2
> parts, -> Sum(just positive values)/n and Sum(just negative values)/n. i
> need both for my regression but dont know how to do it.
>
> for example we have the matrix
>
> 1  1  -1  -1   -> rowMeans([1:3 , 2])  just positive -> 1
> 1 -1 -1  -2
> 1/2  here not 0 because we dont use the -1
> 1 1   1   1
> 1
>
>
> thanks for helping
>
>
>
> --
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