ggplot2 + gridExtra: how to ensure geom_bar in different size plot grobs result in exact same bar width

Question

This question is motivated by further exploring this question. The problem with the accepted solution becomes more obvious when there is a greater disparity in the number of

Answer 1

Something like this appear to work, but it doesn't - not completely. It has the appearance of working because the levels of the ID factor are sequential. Anything else, and scale = "free" fails. But it might be possible to develop further. The method uses facet_grid, and thus space = "free" can be used. The method uses geom_rect to layer differently coloured rectangles on top of each other. It needs cumulative sums to be calculated so that the right-hand edge of each rectangle can be positioned.

data <- data.frame(ID=factor(c(rep(1,9), rep(2,6), rep(3,6), rep(4,3), rep(5,3))),
                   TYPE=factor(rep(1:3,3)),
                   TIME=factor(c(1,1,1,2,2,2,3,3,3,1,1,1,2,2,2,1,1,1,2,2,2,1,1,1,1,1,1)),
                   VAL=runif(27))

library(ggplot2)
library(plyr)

# Get the cumulative sums
data = ddply(data, .(ID, TIME), mutate, CUMSUMVAL = cumsum(VAL))

ggplot(data, aes(x=VAL, y = as.numeric(ID), fill=TYPE)) +
   geom_rect(data = subset(data, TYPE == 3), aes(xmin = 0, xmax = CUMSUMVAL, ymin = as.numeric(ID)-.2, ymax = as.numeric(ID)+.2)) +
   geom_rect(data = subset(data, TYPE == 2), aes(xmin = 0, xmax = CUMSUMVAL, ymin = as.numeric(ID)-.2, ymax = as.numeric(ID)+.2)) +
   geom_rect(data = subset(data, TYPE == 1), aes(xmin = 0, xmax = CUMSUMVAL, ymin = as.numeric(ID)-.2, ymax = as.numeric(ID)+.2)) +
   facet_grid(TIME~., space = "free", scale="free") +
   scale_y_continuous(breaks = c(1:5), expand = c(0, 0.2))

EDIT: OR really thick lines work a little better (I think)

ggplot(data, aes(x=VAL, y = ID, colour=TYPE)) +
       geom_segment(data = subset(data, TYPE == 3), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
       geom_segment(data = subset(data, TYPE == 2), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
       geom_segment(data = subset(data, TYPE == 1), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
       facet_grid(TIME~., space = "free", scale="free") 

Additional Edit Taking the data from your earleir post, and modifying it a little.
Updated opts is deprecated; using theme instead.

df <- structure(list(ID = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 
2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 
5L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L, 6L, 6L, 7L, 7L, 7L), .Label = c("a", 
"b", "c", "d", "e", "f", "g"), class = "factor"), TYPE = structure(c(1L, 
2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 6L, 1L, 2L, 3L, 4L, 5L, 6L, 
1L, 2L, 3L, 4L, 5L, 6L, 1L, 2L, 3L, 4L, 5L, 6L, 1L, 2L, 3L, 4L, 
5L, 6L, 1L, 2L, 3L), .Label = c("1", "2", "3", "4", "5", "6", 
"7", "8"), class = "factor"), TIME = structure(c(2L, 2L, 2L, 
2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 
2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 3L, 3L, 3L, 3L, 3L, 3L, 
1L, 1L, 1L), .Label = c("One", "Five", "Fifteen"), class = "factor"), VAL = c(0.937377670081332, 
0.522220720537007, 0.278690102742985, 0.967633064137772, 0.116124767344445, 
0.0544306698720902, 0.470229141646996, 0.62017166428268, 0.195459847105667, 
0.732876230962574, 0.996336271753535, 0.983087373664603, 0.666449476964772, 
0.291554537601769, 0.167933790013194, 0.860138458199799, 0.172361251665279, 
0.833266809117049, 0.620465772924945, 0.786503327777609, 0.761877260869369, 
0.425386636285111, 0.612077651312575, 0.178726130630821, 0.528709076810628, 
0.492527724476531, 0.472576208412647, 0.0702785139437765, 0.696220921119675, 
0.230852259788662, 0.359884874196723, 0.518227979075164, 0.259466265095398, 
0.149970305617899, 0.00682218233123422, 0.463400925742462, 0.924704828299582, 
0.229068386601284)), .Names = c("ID", "TYPE", "TIME", "VAL"), row.names = c(NA, 
-38L), class = "data.frame")

library(ggplot2)
library(plyr)

data = ddply(df, .(ID, TIME), mutate, CUMSUMVAL = cumsum(VAL))

ggplot(data, aes(x=VAL, y = ID, colour=TYPE)) +
           geom_segment(data = subset(data, TYPE == 6), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
           geom_segment(data = subset(data, TYPE == 5), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
           geom_segment(data = subset(data, TYPE == 4), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
           geom_segment(data = subset(data, TYPE == 3), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
           geom_segment(data = subset(data, TYPE == 2), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
           geom_segment(data = subset(data, TYPE == 1), aes(x = 0, xend = CUMSUMVAL, y = ID, yend = ID), size = 10) +
           facet_grid(TIME~., space = "free", scale="free") +
           theme(strip.text.y = element_text(angle = 0))

Answer 2

Changing the gtable doesn't help, unfortunately, as the bar width is in relative units,

g = ggplot_gtable(ggplot_build(p))
panels = which(sapply(g$heights, attr, "unit") == "null")
g$heights[[panels[1]]] <- unit(5, "null")
g$heights[[panels[2]]] <- unit(3, "null")
g$heights[[panels[3]]] <- unit(1, "null")
grid.draw(g)