Recode a variable using data.table package

Question

If I want to recode a variable in R using data.table, what is the syntax? I saw some ans but didn\'t find them appropriate.

e.g. if I have the variable cal

Answer 1

You can do it this way

library(data.table)
trips <- data.table(Name=c('John','Tina','Dave','Casper'),gender=c(1,2,1,0))
trips[,gender:= ifelse(gender == 0 , "Unknown", 
                        ifelse(gender == 1 ,  "Male", 
                                              "Female" ))]

Two problems in your code:

• You need to use := which is the assigning symbol for a column in data.table
• You can only have one alternative with ifelse, so you need another ifelse for the third case: if gender is not 0 then you need to test if gender is 1 to separate the Male and Female cases