[R] counts of each column that are not NA, and/or greater than column means

[Gabor Csardi]

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.
> 
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> 
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-- 
Csardi Gabor <csardi at rmki.kfki.hu>    UNIL DGM