# [R] help with element-by-element sum with NA

R. Michael Weylandt michael.weylandt at gmail.com
Tue Jul 24 06:48:19 CEST 2012

```Perhaps something like:

Reduce(function(x,y){x[is.na(x)] <- 0; y[is.na(y)] <- 0; x + y}, list(A,B,C))

Not the most elegant, but it will get the job done.

Michael

On Mon, Jul 23, 2012 at 3:47 PM, Thiago Couto <couto.thiagoba at gmail.com> wrote:
> Hi,
>
>     I have three matrices which could be, for example:
>     A =  0, NA
>            NA, 3
>
>     B =  1, NA
>             0, NA
>
>     C = 1, NA
>             1, 1
>
>     (The point is that they all may have NA's in some cells)
>
>     QUESTION: How do I perform a element-by-element sum of the elements of
>     these three matrices (A + B + C), ignoring NA's, to obtain:
>
>     D = 2, NA
>            1, 4
>
>     In reality I am handling much larger matrices (not just 2x2).
>
>     Thank you for any help!
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help