Sort data frame by two columns (with condition) [d

问题:

This question already has answers here:

How to sort a dataframe by multiple column(s) (19 answers)

Closed 4 years ago.

I have the following data frame in R:

DataTable <- data.frame( Name = c("Nelle","Alex","Thomas","Jeff","Rodger","Michi"), Age = c(17, 18, 18, 16, 16, 16), Grade = c(1,5,3,2,2,4) )

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

Now ill will sort this data frame by its Age column. No problem so far:

DataTable_sort_age <- DataTable[with(DataTable, order(DataTable[,2])),]

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

There are more persons in the Name columns that have the same age and they should be sorted alphabetically. If the condition, that more than one person is at the same age, is true the data frame should be sorted alphabetically by Name. The output should look like this:

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

Hope you can help me by sorting the data frame alphabetically.

回答1:

As per @Stezzo 's comment updating the answer

Just add, DataTable[, 1] in the order function

DataTable[order(DataTable[,2], DataTable[, 1]),]

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

Remember, the order in which parameters are passed matters. It would first sort the DataTable dataframe w.r.t 2nd column and in case of a tie it would consider the second parameter which is the first column.

回答2:

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.