Hello Will,

z=matrix(c(1,2,3,4,5,6), 2,byrow=T)
min=apply(z,1,min)

what do you need isapply
?apply and its family are very helpful.

apply( matrix, columns, function)
apply( matrix, rows, function)
Check   ?apply


 

Cheers

Anna



Anna Freni Sterrantino
Ph.D Student 
Department of Statistics
University of Bologna, Italy
via Belle Arti 41, 40124 BO.




________________________________
Da: Will Glass-Husain <wglasshusain@gmail.com>
A: r-help@stat.math.ethz.ch
Inviato: Giovedì 29 gennaio 2009, 17:58:50
Oggetto: [R] Taking the min of each row in a matrix

Hi,

I'm a new user. I've been reading through the manual and looking at
various examples but am still trying to make sense of the most
efficient ways to handle matrices of data.

If I have a 2D matrix of data, how do I get the mean, min, max value
of each row?  I see the "mean" function on a matrix will give me
averages by row, but min and max give me the value for the entire
matrix.  I want the min (for example) of each row.  pmin looks useful,
but I can't seem to get the syntax right to apply to each column.

Right now I am doing this.  Is there a one-liner that would work instead?

minResult <- vector (mode="list", length=rowCount)
for (row in 1:rowCount)
{
    minResult[[row]] <- min(corResult[row], na.rm = TRUE)            
}

Thanks in advance.

WILL

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