Using lapply to create new columns based on old columns

Question

My data looks as follows:

DF <- structure(list(No_Adjusted_Gross_Income = c(183454, 241199, 249506
), NoR_from_1_to_5000 = c(1035373, 4272260, 1124098), NoR_f         


        

Answer 1

This should work.. lapply() is not needed

library( data.table )
setDT( DF )
DF[, (var) := as.data.table ( t( t( DF[, 2:3] ) * val ) ) ][]


#    No_Adjusted_Gross_Income NoR_from_1_to_5000 NoR_from_5000_to_10000 AGI_from_1_to_5000 AGI_from_5000_to_10000
# 1:                   183454            1035373                 319540         2588950187             2396550000
# 2:                   241199            4272260                4826042        10682786130            36195315000
# 3:                   249506            1124098                1959866         2810807049            14698995000