Sort data frame by two columns (with condition) [duplicate]

Answer 1

in addition to @Ronak Shah answer you can also use arrange of dplyr. It looks a bit simpler to me.

arrange(DataTable,Age,Name)

gives

    Name Age Grade
1   Alex  16     3
2   Jeff  16     2
3  Michi  16     4
4 Rodger  16     2
5  Nelle  17     1
6   Alex  18     5
7 Thomas  18     4

Here, it first sorts by Age then Name and you can add more variables so on.