[R] Sum with condition

[Sarah Goslee]

Hi,

On Wed, Nov 2, 2011 at 8:44 AM, Celine <bellard.celine at gmail.com> wrote:
> CELLCD AreaProtected
>   8928      52.39389
>   8928      41.91511
>   8929      21.21975
>   8929      63.65925
>   8930      26.08547
>   8930      14.04602

You'll need to figure out how you want it to be combined with the
original data frame, since there can't be empty cells, but:

> dput(testdata)
structure(list(CELLCD = c(8928L, 8928L, 8929L, 8929L, 8930L,
8930L), AreaProtected = c(52.39389, 41.91511, 21.21975, 63.65925,
26.08547, 14.04602)), .Names = c("CELLCD", "AreaProtected"), class =
"data.frame", row.names = c(NA,
-6L))
>
> aggregate(testdata$AreaProtected, by=list(CELLCD=testdata$CELLCD), FUN="sum")
  CELLCD        x
1   8928 94.30900
2   8929 84.87900
3   8930 40.13149


-- 
Sarah Goslee
http://www.functionaldiversity.org