How do I convert all numeric columns to character type in my dataframe?

Question

I would like to do something more efficient than

dataframe$col <- as.character(dataframe$col)

since I have many numeric columns.

Answer 1

In base R, we may either use one of the following i.e. loop over all the columns, create an if/else conditon to change it

dataframe[] <- lapply(dataframe, function(x) if(is.numeric(x)) 
           as.character(x) else x)

Or create an index for numeric columns and loop only on those columns and assign

i1 <- sapply(dataframe, is.numeric)
dataframe[i1] <- lapply(dataframe[i1], as.character)

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It may be more flexible in dplyr

library(dplyr)
dataframe <- dataframe %>%
        mutate(across(where(is.numeric), as.character))