Multirow axis labels with nested grouping variables
A very simple solution which gives a similar (though not identical) result is to use faceting. The downside is that the Category label is above rather than below.
ggplot(data=data, aes(x=Group, y=Value, fill=Group)) +
geom_bar(position = 'dodge', stat="identity") +
geom_text(aes(label=paste(Value, "%")), position=position_dodge(width=0.9), vjust=-0.25) +
facet_grid(. ~ Category) +
theme(legend.position="none")
You can create a custom element function for axis.text.x
.
library(ggplot2)
library(grid)
## create some data with asymmetric fill aes to generalize solution
data <- read.table(text = "Group Category Value
S1 A 73
S2 A 57
S3 A 57
S4 A 57
S1 B 7
S2 B 23
S3 B 57
S1 C 51
S2 C 57
S3 C 87", header=TRUE)
# user-level interface
axis.groups = function(groups) {
structure(
list(groups=groups),
## inheritance since it should be a element_text
class = c("element_custom","element_blank")
)
}
# returns a gTree with two children:
# the categories axis
# the groups axis
element_grob.element_custom <- function(element, x,...) {
cat <- list(...)[[1]]
groups <- element$group
ll <- by(data$Group,data$Category,I)
tt <- as.numeric(x)
grbs <- Map(function(z,t){
labs <- ll[[z]]
vp = viewport(
x = unit(t,'native'),
height=unit(2,'line'),
width=unit(diff(tt)[1],'native'),
xscale=c(0,length(labs)))
grid.rect(vp=vp)
textGrob(labs,x= unit(seq_along(labs)-0.5,
'native'),
y=unit(2,'line'),
vp=vp)
},cat,tt)
g.X <- textGrob(cat, x=x)
gTree(children=gList(do.call(gList,grbs),g.X), cl = "custom_axis")
}
## # gTrees don't know their size
grobHeight.custom_axis =
heightDetails.custom_axis = function(x, ...)
unit(3, "lines")
## the final plot call
ggplot(data=data, aes(x=Category, y=Value, fill=Group)) +
geom_bar(position = position_dodge(width=0.9),stat='identity') +
geom_text(aes(label=paste(Value, "%")),
position=position_dodge(width=0.9), vjust=-0.25)+
theme(axis.text.x = axis.groups(unique(data$Group)),
legend.position="none")
An alternative to agstudy's method is to edit the gtable and insert an "axis" calculated by ggplot2,
p <- ggplot(data=data, aes(x=Category, y=Value, fill=Group)) +
geom_bar(position = position_dodge(width=0.9),stat='identity') +
geom_text(aes(label=paste(Value, "%")),
position=position_dodge(width=0.9), vjust=-0.25)
axis <- ggplot(data=data, aes(x=Category, y=Value, colour=Group)) +
geom_text(aes(label=Group, y=0),
position=position_dodge(width=0.9))
annotation <- gtable_filter(ggplotGrob(axis), "panel", trim=TRUE)
annotation[["grobs"]][[1]][["children"]][c(1,3)] <- NULL #only keep textGrob
library(gtable)
g <- ggplotGrob(p)
gtable_add_grobs <- gtable_add_grob # let's use this alias
g <- gtable_add_rows(g, unit(1,"line"), pos=4)
g <- gtable_add_grobs(g, annotation, t=5, b=5, l=4, r=4)
grid.newpage()
grid.draw(g)
The strip.position
argument in facet_wrap()
and switch
argument in facet_grid()
since ggplot2 2.2.0 now makes the creation of a simple version of this plot fairly straightforward via faceting. To give the plot the uninterrupted look, set the panel.spacing
to 0.
Here's the example using the dataset with a different number of Groups per Category from @agtudy's answer.
- I used
scales = "free_x"
to drop the extra Group from the Categories that don't have it, although this won't always be desirable. - The
strip.position = "bottom"
argument moves the facet labels to the bottom. I removed the strip background all together withstrip.background
, but I could see that leaving the strip rectangle would be useful in some situations. - I used
width = 1
to make the bars within each Category touch - they'd have spaces between them by default.
I also use strip.placement
and strip.background
in theme
to get the strips on the bottom and remove the strip rectangle.
The code for versions of ggplot2_2.2.0 or newer:
ggplot(data = data, aes(x = Group, y = Value, fill = Group)) +
geom_bar(stat = "identity", width = 1) +
geom_text(aes(label = paste(Value, "%")), vjust = -0.25) +
facet_wrap(~Category, strip.position = "bottom", scales = "free_x") +
theme(panel.spacing = unit(0, "lines"),
strip.background = element_blank(),
strip.placement = "outside")
You could use space= "free_x"
in facet_grid()
if you wanted all the bars to be the same width regardless of how many Groups per Category. Note that this uses switch = "x"
instead of strip.position
. You also might want to change the label of the x axis; I wasn't sure what it should be, maybe Category instead of Group?
ggplot(data = data, aes(x = Group, y = Value, fill = Group)) +
geom_bar(stat = "identity", width = 1) +
geom_text(aes(label = paste(Value, "%")), vjust = -0.25) +
facet_grid(~Category, switch = "x", scales = "free_x", space = "free_x") +
theme(panel.spacing = unit(0, "lines"),
strip.background = element_blank(),
strip.placement = "outside") +
xlab("Category")
Older code versions
The code for ggplot2_2.0.0, when this feature was first introduced, was a little different. I've saved it below for posterity:
ggplot(data = data, aes(x = Group, y = Value, fill = Group)) +
geom_bar(stat = "identity") +
geom_text(aes(label = paste(Value, "%")), vjust = -0.25) +
facet_wrap(~Category, switch = "x", scales = "free_x") +
theme(panel.margin = unit(0, "lines"),
strip.background = element_blank())