data.table join (multiple) selected columns with new names

Question

I like to join two tables that have some identical columns (names and values) and others that are not. I\'m only interested in joining those that are not identical and I wou

Answer 1

Updated answer based on Arun's recommendation:

cols_old <- c('i.a', 'i.b')
DT1[DT2, (cols_new) := mget(cols_old), on = c(id = "id")]

you could also generate the cols_old by doing:

paste0('i.', gsub('_new', '', cols_new, fixed = TRUE))

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See history for the old answer.