I am trying to sort a vector of strings by the frequency of tis values.

For instance:

```
x = ["a", "b", "b", "c", "c", "c"]
```

Since there are 3 `"c"`

, 2 `"b"`

and 1 `"a"`

, I would like to get a vector of uniques in that order:

```
["c", "b", "a"]
```

Currently, I’ve managed to count the existing values:

```
using StatsBase
x = ["a", "b", "b", "c", "c", "c"]
string_count = StatsBase.countmap(x)
Dict("c"=>3,"b"=>2,"a"=>1)
```

This returns a dict with frequencies (well, the number of each element), but I am stuck at trying to transform this into a sorted vector of uniques…

I believe one could extract the keys and values as two columns of a dataframe, sort this dataframe by the `number`

and then extract the column of `values`

, but it seems a bit inefficient…