[R] How to force aggregate to exclude NA ?

[Gabor Grothendieck]

Try

aggregate(m[, -(1:2)], m[1], sum, na.rm = TRUE)
aggregate(!is.na(m[, -(1:2)]), m[1], sum, na.rm = TRUE)

# or (this uses row names rather than a column for the group):

rowsum(m[, -(1:2)], m[,1], na.rm = TRUE)
rowsum(0+!is.na(m[, -(1:2)]), m[,1], na.rm = TRUE)


On Sun, Dec 7, 2008 at 7:06 AM, Daren Tan <daren76 at hotmail.com> wrote:
>
> The aggregate function does "almost" all that I need to summarize a datasets, except that I can't specify exclusion of NAs without a little bit of hassle.
>
>> set.seed(143)
>> m <- data.frame(A=sample(LETTERS[1:5], 20, T), B=sample(LETTERS[1:10], 20, T), C=sample(c(NA, 1:4), 20, T), D=sample(c(NA,1:4), 20, T))
>> m
>   A B  C  D
> 1  E I  1 NA
> 2  A C NA NA
> 3  D I NA  3
> 4  C I  2  4
> 5  A C  3  2
> 6  E J  1  2
> 7  D J  2  2
> 8  C G  4  1
> 9  C D NA  3
> 10 B G  3 NA
> 11 C B  4  2
> 12 A B NA NA
> 13 E A NA  4
> 14 B B  3  3
> 15 E I  4  1
> 16 E J  3  1
> 17 B J  4  4
> 18 B J  1  3
> 19 D D  4  2
> 20 B B  4  3
>
>> aggregate(m[,-c(1:2)], by=list(m[,1]), sum)
>  Group.1  C  D
> 1       A NA NA
> 2       B 15 NA
> 3       C NA 10
> 4       D NA  7
> 5       E NA NA
>
>> aggregate(m[,-c(1:2)], by=list(m[,1]), length)
>  Group.1 C D
> 1       A 3 3
> 2       B 5 5
> 3       C 4 4
> 4       D 3 3
> 5       E 5 5
>
> My own defined version of length and sum to exclude NA
>
>> mylength <- function(x) {  sum(as.logical(x), na.rm=T) }
>> mysum <- function(x) {sum(x, na.rm=T)}
>
>> aggregate(m[,-c(1:2)], by=list(m[,1]), mysum)   <----------------- this computes correctly.
>  Group.1  C  D
> 1       A  3  2
> 2       B 15 13
> 3       C 10 10
> 4       D  6  7
> 5       E  9  8
>
>> aggregate(m[,-c(1:2)], by=list(m[,1]), mylength) <----------------- this computes correctly.
>  Group.1 C D
> 1       A 1 1
> 2       B 5 4
> 3       C 3 4
> 4       D 2 3
> 5       E 4 4
>
> There are other statistics I need to compute e.g. var, sd, and it is a hassle to create customized versions to exclude NA. Any alternative approaches ?
>
>
>
>
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