[R] counts of each column that are not NA, and/or greater than column means
Gabor Csardi
csardi at rmki.kfki.hu
Mon Feb 4 09:32:33 CET 2008
On Mon, Feb 04, 2008 at 03:21:10PM +0800, Ng Stanley wrote:
> Hi,
>
> Given a test matrix, test <- matrix(c(1,2,3,NA,2,3,NA,NA,2), 3,3)
>
> A) How to compute the counts of each column (excluding the NA) i.e., 3, 2, 1
apply(test, 2, function(x) sum(!is.na(x)))
> B) How to compute the counts of each column (excluding the NA) that are
> greater than the column means ? i.e., 1, 1, 0
apply(test, 2, function(x) sum(x > mean(x, na.rm=TRUE), na.rm=TRUE))
In general, you need ?apply to calculate something for each row/column
of a matrix.
Gabor
> I could write a for loop, but hope to use better alternative.
>
> [[alternative HTML version deleted]]
>
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--
Csardi Gabor <csardi at rmki.kfki.hu> UNIL DGM
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