here is a solution with expand.grid(),
a <- c(2,2,3,4,5,6,7,8,9)
a.cut <- cut(a, breaks=c(0,2,6,9,12,13,15,16), right=FALSE )
x <- data.frame(a, a.cut)
out <- expand.grid(a = 0, a.cut = setdiff(levels(a.cut), unique(a.cut)))
rbind(out, x)
I hope it helps.
Best,
Dimitris
On 6/14/2011 1:32 PM, Patrick Hausmann wrote:
Dear list,
I would like to expand a DF with all the missing levels of a variable.
a <- c(2,2,3,4,5,6,7,8,9)
a.cut <- cut(a, breaks=c(0,2,6,9,12), right=FALSE )
(x <- data.frame(a, a.cut))
# In 'x' the level "[0,2)" is "missing".
AddMissingLevel <- function(xdf) {
xfac <- factor( c("[0,2)", "[2,6)", "[6,9)", "[9,12)") )
xlevels <- levels(xfac)
if(length(xlevels) != nlevels(factor(xdf$a.cut))) {
v <- setdiff(xlevels, factor(xdf$a.cut))
u <- data.frame(a = 0, a.cut = v)
x <- rbind(u, x)
}
return(x)
}
AddMissingLevel(x)
Does a more general approach exist, e.g. using "expand.grid"?
Thanks for any help!!
Patrick
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--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/
______________________________________________
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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.
