using predict with a list of lm() objects

Question

I have data which I regularly run regressions on. Each \"chunk\" of data gets fit a different regression. Each state, for example, might have a different function that expla

Answer 1

You need to use mdply to supply both the model and the data to each function call:

dataList <- dlply(newData, "state")

preds <- mdply(cbind(mod = modelList, df = dataList), function(mod, df) {
  mutate(df, pred = predict(mod, newdata = df))
})