[R] select element from each row of the matrix
Peter.Alspach at plantandfood.co.nz
Wed Jul 20 22:35:37 CEST 2011
Assuming your matrix is called yourMatrix, then try
apply(yourMatrix, 1, function(x) which(x<=5))
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of gallon li
> Sent: Thursday, 21 July 2011 8:23 a.m.
> To: R-help at r-project.org
> Subject: [R] select element from each row of the matrix
> I have a 5 column matrix like
> 12 10 8 6 3
> 10 9 8 7 5
> 14 NA 4 NA NA NA
> 15 NA 10 NA 5
> I want to select the position of the first entry for each row <=5
> for example, for the first row, I want to select the last element and
> its position as 5;
> for th e third row, I want to select the third element and return its
> position as 3;
> similarly for the 4th row, I want to select the fifth element and
> return its
> position 5.
> I am wondering how to do this fast? Thanks a lot!
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