Two legend bugs

[tdhock]

## BUG 1: the fill legend should use shape=21 so that I can see color
## differences in the legend and decode the fill aesthetic.
df <- data.frame(x=1:3,y=1:3,
                 fill=c("B","R","R"),
                 shape=c("circle","circle","cross"))
p <- ggplot(df)+
  geom_point(aes(x, y, fill=fill, shape=shape))+
  scale_shape_manual(values=c(circle=21,cross=13))+
  scale_fill_manual(values=c(B="blue",R="red"))
print(p)

## BUG 2: previous problem, plus too many items in the shape legend.
df <- data.frame(x=1:3,y=1:3,fill=factor(c(1,2,2)),shape=c(21,21,13))
p <- ggplot(df)+
  geom_point(aes(x, y, fill=fill, shape=shape))+
  scale_shape_identity(guide="legend")+
  scale_fill_identity(guide="legend")
print(p)

[BrianDiggs]

Here are workarounds for these two issues (I'm not saying they aren't bugs, just that there exists a way to get what you want):

ggplot(df)+
  geom_point(aes(x, y, fill=fill, shape=shape))+
  scale_shape_manual(values=c(circle=21,cross=13))+
  scale_fill_manual(values=c(B="blue",R="red"), 
                    guide=guide_legend(override.aes=aes(shape=21)))

and

ggplot(df)+
  geom_point(aes(x, y, fill=fill, shape=shape))+
  scale_shape_identity(guide="legend", breaks=c(13,21))+
  scale_fill_identity(guide="legend")

(bearing in mind that df is different for the two examples).

[hadley]

This sounds like a great feature/horrible bug, but unfortunately we don't currently have the development bandwidth to support it/fix it. If you'd like to submit a pull request that implements this feature/fixes this bug, please follow the instructions in the development vignette.

[devu123]

+1 for fixing this in newer versions, or direction for a pull request;
I would like to help with a generalized solution for a graph with an unknown number of shapes/groups,
with unknown names before plotting.