Hi:

> z = matrix(rnorm(n*m),n,m,dimnames =list(rnames,cnames))
> z
           x1          x2           x3         x4          x5
1  -0.3942900 -0.61202639 -1.804958629 -0.1351786 -1.27659221
2  -0.0593134  0.34111969  1.465554862  1.1780870 -0.57326541
3   1.1000254 -1.12936310  0.153253338 -1.5235668 -1.22461261
4   0.7631757  1.43302370  2.172611670  0.5939462 -0.47340064
5  -0.1645236  1.98039990  0.475509529  0.3329504 -0.62036668
6  -0.2533617 -0.36722148 -0.709946431  1.0630998  0.04211587
7   0.6969634 -1.04413463  0.610726353 -0.3041839 -0.91092165
8   0.5566632  0.56971963 -0.934097632  0.3700188  0.15802877
9  -0.6887557 -0.13505460 -1.253633400  0.2670988 -0.65458464
10 -0.7074952  2.40161776  0.291446236 -0.5425200  1.76728727
11  0.3645820 -0.03924000 -0.443291873  1.2078678  0.71670748
12  0.7685329  0.68973936  0.001105352  1.1604026  0.91017423
13 -0.1123462  0.02800216  0.074341324  0.7002136  0.38418536
14  0.8811077 -0.74327321 -0.589520946  1.5868335  1.68217608
15  0.3981059  0.18879230 -0.568668733  0.5584864 -0.63573645
> z[z[, 1] < 0, ]
           x1          x2          x3         x4          x5
1  -0.3942900 -0.61202639 -1.80495863 -0.1351786 -1.27659221
2  -0.0593134  0.34111969  1.46555486  1.1780870 -0.57326541
5  -0.1645236  1.98039990  0.47550953  0.3329504 -0.62036668
6  -0.2533617 -0.36722148 -0.70994643  1.0630998  0.04211587
9  -0.6887557 -0.13505460 -1.25363340  0.2670988 -0.65458464
10 -0.7074952  2.40161776  0.29144624 -0.5425200  1.76728727
13 -0.1123462  0.02800216  0.07434132  0.7002136  0.38418536


Is this what you were looking for?

HTH,
Dennis

On Tue, Feb 9, 2010 at 12:12 PM, DonDiego <jorge.nieves@moorecap.com> wrote:

>
> Hi,
>
> I have a matrix of data values like the example bellow. I would like to
> extract a subset of the matrix for the values where the first column is
> negative.  I am using the subset function. However, I am getting an error
> message that the conditional variable doe snot exist.  For some reason, the
> subset operation only works if I transform the matrix to a data set using
> as.data.set(). The help indicates that the subset function can be applied
> to
> matrixes and data sets. I am wondering if anyone has seen a similar problem
> before. am I using the correct syntax?
>
>
>
> n = 15
> m = 5
>
> cnames = paste("x",1:m,sep="")
> rnames = 1:n
>
> z = matrix(rnorm(n*m),n,m,dimnames =list(rnames,cnames))
>
>
> Thanks,
>
> Jorge
>
>
>
>
> test = subset(z,x1 < 0, select = c(cnames))
>
> --
> View this message in context:
> http://n4.nabble.com/subset-in-a-matrix-tp1474958p1474958.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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