r - Update class of a subset of columns in data.table -


i want change couple of data.table columns factor character

library(data.table)  ir <- as.data.table(iris) ir[, species2 := species]

i can identify columns need change

facs <- which(sapply(ir, is.factor)) facs

and can update columns name:

ir[, c("species", "species2") := lapply(.sd, as.character), .sdcols = facs] sapply(ir, class)

is there way update columns without referencing them name?

you're close. @akrun mentioned in comment, can reference columns index, you've obtained using which.

ir[, which(sapply(ir, is.factor)) := lapply(.sd, as.character), .sdcols = facs]

or better, @frank mentioned in comment, can use parentheses.

ir[, (fac) := lapply(.sd, as.character), .sdcols = fac]

now if @ str(ir), you'll see species , species2 chr rather factor.


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