How to create logical variables out of multilevel factor in R

Question

I want to create logical variables for every level of factor x.

so from a factor x <- factor(c('apple','orange','apple','peach')) I would get three variables each the length of x:

apple = c(T,F,T,F)
orange = c(F,T,F,F)
peach = c(F,F,F,T)

Is there a function to do this?

Possible duplicate [How to create dummy variables](http://stackoverflow.com/q/12758075/903061). — Gregor Thomas, Jan 06 '16 at 20:10
Better possible dupe: [Generate a dummy variable in R](http://stackoverflow.com/q/11952706/903061). — Gregor Thomas, Jan 06 '16 at 20:11

score 1 · Accepted Answer · answered Jan 06 '16 at 20:07

1

Try this. It creates a data frame of those vectors:

x <- as.factor(c('apple','orange','apple','peach'))
df <- data.frame(sapply(levels(x), function(l) l == x))

answered Jan 06 '16 at 20:07

Gopala

exactly what I needed, but would you explain what the `function(l) l==x` does? Oh I get it... so simple... – WojciechF Jan 06 '16 at 20:10
sapply will iterative take each level of the factor from levels(x), passes each to the function where l is one of the levels. Then, l == x is checking which of the x values match the single level passed l. This operation will return a true/false vector for that single level. – Gopala Jan 06 '16 at 20:12
You can try out by simply doing 'apple' == x to see. – Gopala Jan 06 '16 at 20:13

1 Answers1