stat
stat
can be "identity"
(we specify the value of the y manually, like in a scatterploy) or "count"
(in which case the special values ..count..
and ..prop..
are computed and can be mapped to the y axis). bin
is another option, but we use geom_histogram
for that.
position
position
can be "identity"
, in which case the bars are displayed according to the x value without modification (overlayed on each other as necessary), "dodge"
, in which bars that would otherwise overlap are displayed side-by side (“dodging” each other), or "stack"
, in which case bars with the same x value are stacked on top of each other. When using position = "identity"
it often makes sense to specify alpha = 0.5
(or something like that) to make the bars semi-transparent.
group
See Healy Ch. 4.4
geom_histogram
geom_histogram
is just geom_bar
with stat = "bin"
. All the different position
values discussed above can be used.