So I've got a dataset that looks something like this:

```
a   b   c
23  34  Falcons
14  9   Hawks
2   18  Eagles
3   21  Eagles
22  8   Falcons
11  4   Hawks

```

And I know I can do a random subset of rows [with a nested conditional](https://stackoverflow.com/questions/19989355/extracting-a-random-sample-of-rows-in-a-data-frame-with-a-nested-conditional), but what I want to do is create a random subset that takes **at least one of each available value in column 'c'**.

So possible correct subsets would be 

```
23  34  Falcons
14  9   Hawks
3   21  Eagles

```

or

```
11  4   Hawks
2   18  Eagles
22  8   Falcons

```

[in no particular order], but something like:

```
14  9   Hawks
2   18  Eagles
3   21  Eagles

```

would NOT work, because 'Falcons' is not represented. Is there an easy way to do this in R?