hadley/ggplot2 — comment on commit 173094a923eb2ece8c57887755eca4e45df7b67d
File: R/geom-dotplot.r line 26
By briandk:

> The dotstack grob does the work of putting the dots next to each other. It's kind of complicated, but in a nutshell, it's because the dots have to be stacked visually, and it's not possible to do that at the geom level.

@wch - I think I understand that. But, I have a hunch that setting x = 0 is a poor substitute. Compare the graphics produced by this code:

```r

# coord_flip version
p <- ggplot(mtcars, aes(x = mpg)
p <- p + geom_dotplot(data = mtcars, binwidth = 1.5, binaxis = "x")
p + coord_flip()

# using x = 1
ggplot(mtcars, aes(x = 0, y = mpg)) +
geom_dotplot(binaxis = "y", stackdir = "up")
```

[![Comparison of dot plots with coord_flip (left) and setting x = 0 (right)][1]][1]

* The x-axis labels don't match, and even if they were identical,
* "count" as an axis label becomes meaningless when setting `x = 0` since it's impossible that the dots in the right-hand plot sum to a count of 1.0

[1]: http://briandk.com/screenshots/DotplotComparison-20120226-031641.png