[R] length with missing values

[Petr Pikal]

On 15 Oct 2004 at 12:01, Luis Rideau Cruz wrote:

> R-help
> 
> I have a martix with missing values( in which I want the sample size
> by column) When I :
> 
> apply(matrix,2,length)

Hi

Try
apply(matrix, 2, function(x) sum(!is.na(x)))

matrix is reserved word, so it is preferable to use other name for 
your object.

Cheers
Petr

> 
> I get the length of the vector regardless of missing values.
> I can't pass an argument to length in apply.
> 
> Alternatively I could 
> 
> ifelse ( is.na ( matrix [, "columns in matrix " ] ) , 0 , 1)
> 
> Is there any easier way?
> 
> Thank you
> 
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Petr Pikal
petr.pikal at precheza.cz