I have fit a neural net in R:

```
model = nnet(f1/max(f1)~n1+n2+n3+n4+n5+n6+n7+n8+n9+n10+n11+n12,data=md,size=3)

```

From the model object I can extract the formula of the call, `model$call$formula`, which returns an object of type `call` and appears to be a list of length 3. I know I can use `as.formula()` on the `call` object in the `nnet()` call but I don't know how to edit it first.

What I want to do is modify the formula and then pass it back to `nnet()`. Specifically, I'd like to be able to change the dependent variable and add or remove dependent variables.