hadley/ggplot2 — comment on commit 4203f765752adf31a58b5931edaa2d6cc2e2ac51
File: R/geom-path-.r line 39
By kohske:

Here is a small example on what I'm telling:

```
@> as.integer(factor(paste("a", 1:11, sep="_")))
[1] 1 4 5 6 7 8 9 10 11 2 3
```

maybe the possible fix is to use `id.length` instead of `id` in `polylineGrob` like this:

```
polylineGrob(..., id.length = rle(group))
```

In this case, all points in the same line need appear in succession in the data.