Hi Luis,

just use:

apply( mat, 2, function(x) length(x[!is.na(x)]) )

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/396887
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
    http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm


----- Original Message ----- From: "Luis Rideau Cruz" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, October 15, 2004 1:01 PM
Subject: [R] length with missing values



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?

Thank you

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