[R] Matrix elements

[Christos Hatzis]

Since both columns being positive implies that the row wise sum and row wise
product are both positive, you can try the following:

x <- matrix(rnorm(20),ncol=2)

x[apply(x, 1, FUN=function(x) ifelse(sum(x)>0 & prod(x)>0,TRUE,FALSE)),]

-Christos Hatzis 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Akkineni,Vasundhara
Sent: Sunday, March 26, 2006 11:49 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Matrix elements

Hello all,

I have a matrix object, xx given as below:

             [,1]         [,2]
 [1,]  0.02237883  0.601572660
 [2,] -0.39880918  0.126498958
 [3,]  0.20269214  0.567953402
 [4,] -0.45750812 -0.031193600
 [5,] -0.30666134 -0.084819484
 [6,] -0.37718928  0.078675868
 [7,] -0.25432685 -0.005200316
 [8,] -0.22146224  0.168196438
 [9,] -0.32049919 -0.013216047
[10,]  0.94325749  1.341664313

How can i check for every row in the matrix that both the column elements
are greater than zero, and if they are greater than zero then to print the
row number. I tried using for loops, but it kept returning warnings. Please
let me know how this can be done.

Thanks,
Vasu.

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