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))
--
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Try this: z[z[,1] < 0,] On Tue, Feb 9, 2010 at 6:12 PM, DonDiego <jorge.nieves at 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 at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >-- Henrique Dallazuanna Curitiba-Paran?-Brasil 25? 25' 40" S 49? 16' 22" O
Hi:> z = matrix(rnorm(n*m),n,m,dimnames =list(rnames,cnames)) > zx1 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 > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
As others have said, z[z[, 1] < 0, ] does it. Just in case you're wondering why your subset command won't work, str() is your friend (as is so often the case): str(z) str(as.data.frame(z)) ## (I don't think that R has 'as.data.set') So z is a matrix with column *names* "x1", etc; as.data.frame(z) is a data.frame with *variables* named "x1" etc. If you really want to use subset(), then subset(z, z[, "x1"] < 0, select = <...>) will work, but I wouldn't use it. -Peter Ehlers DonDiego 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)) >-- Peter Ehlers University of Calgary