Convert data.frame columns from factors to characters

Question

I have a data frame. Let\'s call him bob:

> head(bob)
                 phenotype                         exclusion
GSM399350 3- 4- 8- 25- 44+         


        

Answer 1

If you would use data.table package for the operations on data.frame then the problem is not present.

library(data.table)
dt = data.table(col1 = c("a","b","c"), col2 = 1:3)
sapply(dt, class)
#       col1        col2 
#"character"   "integer" 

If you have a factor columns in you dataset already and you want to convert them to character you can do the following.

library(data.table)
dt = data.table(col1 = factor(c("a","b","c")), col2 = 1:3)
sapply(dt, class)
#     col1      col2 
# "factor" "integer" 
upd.cols = sapply(dt, is.factor)
dt[, names(dt)[upd.cols] := lapply(.SD, as.character), .SDcols = upd.cols]
sapply(dt, class)
#       col1        col2 
#"character"   "integer"