saschaview wrote on 12/01/2011 12:30:18 PM:
> Hello
>
> I have a data frame, x, holding 5 persons answering the question which
> cars they have used:
>
> # the data frame
> x <- as.data.frame(
> matrix(
> c('BMW', '', '',
> 'Mercedes', 'VW', '',
> 'Skoda', 'VW', 'BMW',
> '', '', '',
> 'VW', 'Skoda', ''
> ),
> ncol=3,
> dimnames=list(
> NULL,
> paste( 'v', 1:3, sep='' )
> )
> )
> )
>
> How do I transform this data frame to a data frame stating whether they
> have used the presented car:
>
> BMW Mercedes VW Skoda
> 1 T F F F
> 2 F T T F
> 3 T F T T
> 4 F F F F
> 5 F F T T
>
> My idea was to first find all levels by:
>
> v <- unique(unlist(lapply(x, levels)))
>
> But then I am stuck.
>
> Thanks for help, *S*
>
> --
> Sascha Vieweg, saschav...@gmail.com
Try this:
uniq.cars <- sort(unique(unlist(x)))
y <- t(apply(x, 1, function(xrow) match(uniq.cars, unique(xrow))))
dimnames(y)[[2]] <- uniq.cars
y2 <- !is.na(y[, -1])
y2
Jean
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