How to convert dataframe columns from factors to characters

Question

I have considered a data frame named 'zz'.

head(zz)
                 phenotype                         exclusion
GSM399350 3- 4- 8- 25- 44+ 11b- 11c- 19- NK1.1- Gr1- TER119-
GSM399351 3- 4- 8- 25- 44+ 11b- 11c- 19- NK1.1- Gr1- TER119-
GSM399352 3- 4- 8- 25- 44+ 11b- 11c- 19- NK1.1- Gr1- TER119-
GSM399353 3- 4- 8- 25+ 44+ 11b- 11c- 19- NK1.1- Gr1- TER119-
GSM399354 3- 4- 8- 25+ 44+ 11b- 11c- 19- NK1.1- Gr1- TER119-
GSM399355 3- 4- 8- 25+ 44+ 11b- 11c- 19- NK1.1- Gr1- TER119-

The following command shows the dataframe has factors

class(zz$phenotype)
[1] "factor"

Now to convert I tried the following command

 as.character(head(zz))
[1] "c(3, 3, 3, 6, 6, 6)"       "c(3, 3, 3, 3, 3, 3)"      
[3] "c(29, 29, 29, 30, 30, 30)"

 I guess these are indices into the levels of the factors of the columns. This is not my desired result.

So any suggestions that can help me?

Answer 1

To replace all the variables to character class you can use the apply statement. Refer below code:

zz <- data.frame(lapply(zz, as.character), stringsAsFactors=FALSE)

You can use the following code to convert only the factor variables to character

i <- sapply(zz, is.factor)
zz[i] <- lapply(zz[i], as.character)

You can also use the dplyr package

library(dplyr)
zz %>% mutate_if(is.factor, as.character) -> 

 Another alternative is to use the purrr package in RStudio:

library(purrr)
library(dplyr)
zz %>% map_if(is.factor, as.character) %>% as_data_frame -> zz