Bar graph in ggplot2 with width as a variable and even spacing between bars

Question

So I am trying to make a stacked bar graph with bar width mapped to a variable; but I want the spacing between my bars to be constant.

Does anyone know how to make t

Answer 1

For a categorical or "discrete" scale - you can adjust the width, but it needs to be between 0 and 1. Your value.x's put it over 1, hence the overlap. You can use rescale, from the scales packages to adjust this quickly so that the within category width of the bar is representative of some other variable (in this case value.x)

install.packages("scales")
library(scales) 
ggplot(dd,aes(x=variable,y=value.y,fill=Date)) +
geom_bar(aes(width=rescale(value.x,c(0.5,1))),stat="identity",position="stack")' +
coord_flip()

Play with rescaling for optimal "view" change 0.5 to 0.25... etc.

Personally, I think something like this is more informative:

ggplot(dd,aes(x=variable,y=value.y,fill=Date)) +
geom_bar(aes(width=rescale(value.x,c(0.2,1))),stat="identity") +
coord_flip() + facet_grid(~Date) + opts(legend.position="none")

Answer 2

Attempt # 2.

I'm tricking ggplot2 into writing a continuous scale as categorical.

# The numbers for tmp I calculated by hand. Not sure how to program 
# this part but the math is 
# last + half(previous_width) + half(current_width)
# Change the 1st number in cumsum to adjust the between category width

tmp <- c(2.91,7.02,14.715,27.75,38.22,46.47,57.845,77.19,101.235) + cumsum(rep(5,9))

dd$x.pos1 <- rep(tmp,each=5)
ggplot(dd,aes(x=x.pos1,y=value.y,fill=Date)) +
geom_bar(aes(width=value.x),stat="identity",position="stack") + 
scale_x_continuous(breaks=tmp,labels=levels(dd$variable)) + 
coord_flip()

For good measure you're probably going to want to adjust the text size. That's done with ... + opts(axis.text.y=theme_text(size=12))