How can I best represent a scatter plot with two different factor variables. Consider the example problem,
df <- data.frame(x=rnorm(300), y=rnorm(300), type=factor(sample(c("a", "b", "c", "d"), 300, replace=T)), class=factor(sample(c("1", "2", "3"), 300, replace=T, prob = c(.7, .25, .05))))
The scatter plot
ggplot(df, aes(x=x, y=y))+geom_point(aes(color=type, shape=class))
looks great on screen, but has poor readability when printed in black and white. On the other hand using
ggplot(df, aes(x=x, y=y))+geom_point()+facet_grid(class~.)
I loose the structure in the data.
So can anyone suggest an alternative plot that looks great in black & white while preserving the data structure. I am wondering if there are any
shape or other aesthetics I can modify.