Using anonymous-function in data.table to change character class

Question

I am writing an anonymous function to loop through a data.table and change any factor variable to a character. I tried the code below, but I receive an error. My actual data.table could have a factor variable in any order, hence why I'm using lapply. Also please share any other ways to do this, but I would like my way answered as well and thanks.

test <- sample[, lapply(.SD, function(x){ 
  if(is.factor(x)){
    as.character(x)}
})
]


sample <- data.table(A = as.factor(1:5), B = as.character(letters[1:5]), C = as.factor(10:14))

Possible duplicate of [Convert data.frame columns from factors to characters](http://stackoverflow.com/questions/2851015/convert-data-frame-columns-from-factors-to-characters) — jangorecki, Feb 25 '16 at 18:09

score 1 · Answer 1 · answered Feb 25 '16 at 17:29

1

You can't refer to x until you've declared it in function(x)

sample[,lapply(.SD, function(x) if(is.factor(x)) as.character(x) else x)]

You don't even need to use data.table syntax:

data.frame(lapply(sample, function(x) if(is.factor(x)) as.character(x) else x))

  A B  C
1 1 a 10
2 2 b 11
3 3 c 12
4 4 d 13
5 5 e 14

answered Feb 25 '16 at 17:29

Señor O

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I get this error message now: Error in .subset(x, j) : invalid subscript type 'list' – user3067851 Feb 25 '16 at 18:01

Using anonymous-function in data.table to change character class

1 Answers1