Remove "a" from legend in plot_intro

[boxuancui]

Reported by @interactivereport via Email:

Boxuan,

I have to use the following code block,

library(ggplot2)
library(DataExplorer)
pdf(file = NULL)
p0 = plot_intro(airquality)
dev.off()

p0 + guides(fill = guide_legend(override.aes = aes(label = "")))

to generate the plot without “a” in legend,

Could you please fix the code?

Thanks,
Baohong

Note to self: Also check if this needs to be updated elsewhere.