Expand DF with all levels of a variable
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/