hadley/ggplot2 — pull request #474 by wch (2012-04-06 21:18:07+00:00)
Title: coord_train.polar: remove NA's in breaks (fix #422)

This fixes #422, in which NA's show up in the theta breaks when using `coord_polar`.

I modified `coord_train.polar()` to do something similar to what `coord_train.cartesian()` does (by calling `train_cartesian()`). See line 87 of [coord-cartesian.r](https://github.com/hadley/ggplot2/blob/master/R/coord-cartesian-.r).

Now `coord_train.polar()` removes `NA`'s that are returned from `scale_breaks()`