[R] length with missing values

[Sundar Dorai-Raj]

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)
> 
> 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?
> 

I think you almost have it:

colSums(ifelse(is.na(x), 0, 1))

will return the number of non-NA elements in each column of x.

Is that what you want?

--sundar