Hi,

I’ve been struggling to find a way to calculate the weighted descriptive statistics in JuliaDB using the groupby function. Assuming that “w” is a column of the table DB with sampling weights, I would like to find something like this:

```
groupby(@NT(avg=z->mean(z, weights(:w)), DB, (:x,:y), select=:z)
```

I understand why the above doesn’t work, but I cannot come up with a way to pass the weights w in the mean (or any other) function.

Thanks!