Modifying data tables

The following makes use of the data.table package. You may need to install it from CRAN using the code install.packages("data.table") if you want to run this on your computer. (The package is already installed on the notebook container, however.)

library(data.table)
UK <- data.table(
           Population = c(55619400,1885400,5424800,3125000),
           Area = c(50301,5460,30090,8023),
           GVA = c(28096,20000,24800,19900),
           country = c("England",
                         "Northern Ireland",
                         "Scotland",
                         "Wales"))

UK1 <- UK
UK[,Density := Population/Area]

UK

  Population Area  GVA   country          Density  
1 55619400   50301 28096 England          1105.7315
2  1885400    5460 20000 Northern Ireland  345.3114
3  5424800   30090 24800 Scotland          180.2858
4  3125000    8023 19900 Wales             389.5052

UK1

  Population Area  GVA   country          Density  
1 55619400   50301 28096 England          1105.7315
2  1885400    5460 20000 Northern Ireland  345.3114
3  5424800   30090 24800 Scotland          180.2858
4  3125000    8023 19900 Wales             389.5052