用因子变量替换数据框中的NA

Question

I would like to create a function to replace NA by the text "NR" in factor variables of a data frame.

I found the below code on the web, that works perfectly :

i <- sapply(data_5, is.factor) # Identify all factor variables in your data
data_5[i] <- lapply(data_5[i], as.character) # Convert factors to character variables
data_5[is.na(data_5)] <- 0 # Replace NA with 0
data_5[i] <- lapply(data_5[i], as.factor) # Convert character columns back to factors

But I would like to transform this code in a function called "remove_na_factor". I tried as below :

remove_na_factor <- function(x){
  i <- sapply(x, is.factor) # Identify all factor variables in your data
  x[i] <- lapply(x[i], as.character) # Convert factors to character variables
  x[is.na(x)] <- "NR" # Replace NA with NR
  x[i] <- lapply(x[i], as.factor) # Convert character columns back to factors

}

When when I run the function on a data frame with NA values, nothing happens ... Thanks in advance for your help.

Answer 1

Just add return(x) at the end of your function:

remove_na_factor <- function(x){
  #your function body
  return(x)
}

You can also get the same result using a tidyverse approach

library(tidyverse)
x %>% 
  mutate_if(is.factor, as.character) %>%   # Convert factors to character variables
  mutate_if(is.character, replace_na, "NR") %>% # Replace NA with NR
  mutate_if(is.character, as.factor)       # Convert character columns back to factors