Getting error while case_when() applied on empty column in R

I have several dataframes with same column names. I wrote a code to perform some operations on a column based on several conditions. But I got error if all the values of that column is empty.

For an example, if my dataframe is like below, my code works fine.

But if my dataframe is like below, my code gives error.

My code is,

data <- data %>%
  mutate(temperature = case_when(
               unit == 'C' ~ temperature, 
               unit == 'F' ~ (temperature - 32)*(5/9),
               unit == 'K' ~ temperature - 273))

Could someone help?

>Solution :

You can force your empty column (it does not matter if it contains empty strings or logical NA’s) to a specific data type, i.e. in this case to a numeric class. Then your case_when() should work and should return NA (NA_real_)

library(dplyr)    

tibble::tribble(~unit, ~temperature,
                    "K","", 
                    "C","", 
                    "F","", 
                    "C", "") %>% 
      mutate(
        temperature = temperature %>% as.numeric(),
        temperature = case_when(
        unit == 'C' ~ temperature, 
        unit == 'F' ~ (temperature - 32)*(5/9),
        unit == 'K' ~ temperature - 273))