I am downloading data from Bloomberg and then update it in R. The dataframe looks as follows. 

```
 ticker       date PX_LAST PE_RATIO
1 SMI Index 2014-09-30 8835.14  20.3692
2 SMI Index 2014-10-31 8837.78  20.3753
3 DAX Index 2014-09-30 9474.30  16.6487
4 DAX Index 2014-10-31 9326.87  16.3896
5 SMI Index 2014-11-28 9150.46  21.0962
6 SMI Index 2014-12-31 8983.37  20.6990
7 DAX Index 2014-11-28 9980.85  17.5388
8 DAX Index 2014-12-31 9805.55  16.8639

```

Now I would like to have this dataframe sorted according to ticker (not in alphabetical order, but in the order of the ticker) and then the date so that the end result would be:

```
 ticker       date PX_LAST PE_RATIO
1 SMI Index 2014-09-30 8835.14  20.3692
2 SMI Index 2014-10-31 8837.78  20.3753
3 SMI Index 2014-11-28 9150.46  21.0962
4 SMI Index 2014-12-31 8983.37  20.6990
5 DAX Index 2014-09-30 9474.30  16.6487
6 DAX Index 2014-10-31 9326.87  16.3896
7 DAX Index 2014-11-28 9980.85  17.5388
8 DAX Index 2014-12-31 9805.55  16.8639

```