bin2d and hex mapped to other scale (alpha)

[Etienne Low-Decarie]

Is it possible to map the value of the bins from bind2d and hex to another scale than fill, notably alpha?  So that the bins with the largest counts are more opaque.

Thank you

[Ista Zahn]

Yes, you can do this as follows:

d <- ggplot(diamonds, aes(carat, price))
d + geom_bin2d(aes(alpha=..count..))

Note that stat_bin2d does not document ..count.. as a return value (as
stat_bin does), so I discovered this by making the educated guess that
stat_bin2d works the same way as ?stat_bin. This really should be
documented.

Best,
Ista

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[Etienne Low-Decarie]

Thank you!  That is great!  Do you know how to get it to map only to alpha (and not to fill)

This does not seem to work:

d <- ggplot(diamonds, aes(carat, price)) 

d + geom_bin2d(aes(alpha=..count..), fill=I("black")) 

Best regards,

Etienne

[Kazimir Menzel]

It works if you include fill specification into the mapping:

d <- ggplot(diamonds, aes(carat, price)) 

d + geom_bin2d(aes(alpha=..count.., fill = NULL)) 

Good luck,

Kazimir.

[Dennis Murphy]

Hi:

Generally speaking, the I() construct is specific to qplot(), but it
doesn't seem to cause any problems here when used with ggplot(). It's
not clear to me which of the two legends you want to remove (I would
guess the colorbar), but try these:

# library(scales)
# Gets rid of the grey scale legend:
d + geom_bin2d(aes(alpha = ..count..), fill = "black") +
scale_alpha(guide = "none")

# Gets rid of the fill colorbar:
d + geom_bin2d(aes(alpha = ..count..), fill = "black") +
scale_fill_continuous(guide = "none")

Dennis