DataTable in R, formatting rows with specific value category to a percentage

Question

If I have a datatable and my goal is to change any rows containing MONTH=\"Percent Change:\" to percentage:

             MONTH YEAR                    Client         


        

Answer 1

We can convert the columns 4 to 8 as character class. Then, using the logical condition in i, we loop over the columns 4 to 8, paste the % and assign (:=) it back to the columns.

library(data.table)
setDT(df)[, (4:8) := lapply(.SD, as.character), .SDcols= 4:8]
df[MONTH=="Percent Change:", (4:8) := 
    lapply(.SD, function(x) paste0(x[!is.na(x)],"%")), .SDcols=4:8]