hadley/ggplot2 — pull request #295 by kohske (2011-12-13 14:22:57+00:00)
Title: Fix a bug in facet-null layout mapping when unusual column name (e.g., `0%`) is used.

Here is the bug report (from boxplot example):

```
> abc <- adply(matrix(rnorm(100), ncol = 5), 2, quantile, c(0, .25, .5, .75, 1))
> ggplot(abc, aes(x = X1, ymin = `0%`, lower = `25%`, middle = `50%`, upper = `75%`, ymax = `100%`)) +
+ geom_boxplot(stat = "identity")
Error in eval(expr, envir, enclos) : object '0%' not found
> ggplot(abc, aes(x = X1, y = `50%`)) + geom_point()
Error in eval(expr, envir, enclos) : object '50%' not found
> abc
X1 0% 25% 50% 75% 100%
1 1 -1.714925 -0.6468398 0.17065804 0.4393230 1.201247
2 2 -1.189586 -0.6724862 -0.09751418 0.4884423 1.134490
3 3 -1.689927 -0.3296100 0.23288596 0.5751145 2.424042
4 4 -1.504052 -0.8237122 -0.33161341 0.3219800 1.507830
5 5 -2.463395 -0.7655001 -0.27450750 0.1631618 1.648378
```

This is because `transform` in `facet_map_layout.null` changes the column name.

```
> transform(abc, P=1)
X1 X0. X25. X50. X75. X100. P
1 1 -2.584666 -0.5943572 0.200944872 0.7742156 2.166626 1
2 2 -2.115618 -0.4283542 0.004670815 0.3936428 1.808468 1
3 3 -2.638751 -0.7368470 -0.265173043 0.4781000 1.571617 1
4 4 -1.476560 -0.3720931 0.182308241 0.8797875 1.924785 1
5 5 -2.999939 -0.6789793 -0.214186432 1.0083131 1.775713 1
```

fixed it.