ggplot's geom_text() labelling of pie chart hides the pie made by geom_bar()

Question

I constructed the following data using the aggregate(,,FUN =sum) function:

    structure(list(Group.1 = structure(c(1L, 2L, 3L, 1L, 2L, 3L, 
1L, 2L, 3L), .Label = c("Black or African American", "White Alone", 
"White Alone LR"), class = "factor"), Group.2 = structure(c(1L, 
1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L), .Label = c("bus", "mixed", "rail"
), class = "factor"), x = c(75143.5182835844, 198737.537113379, 
46973.6469041183, 46199.2335265697, 128026.568239224, 28933.3028730992, 
75876.5845180076, 495166.957025367, 5909.04640985574), pos = c(37571.7591417922, 
99368.7685566897, 23486.8234520592, 98243.1350468693, 262750.821232991, 
61440.2983406679, 159281.044069158, 574347.583865287, 78861.4729821454
), labe = c(" 75,144", "198,738", " 46,974", " 46,199", "128,027", 
" 28,933", " 75,877", "495,167", "  5,909")), class = c("tbl_df", 
"tbl", "data.frame"), .Names = c("Group.1", "Group.2", "x", "pos", 
"labe"), row.names = c(NA, -9L))

I got good code to make a pie chart here and here, which led to this:

modesplit <- ggplot(data = sums) +
  geom_bar( aes(factor(1), y=x, fill=Group.2), stat="identity", position="fill") +
  scale_fill_discrete(guide=guide_legend(title="Mode")) +
  coord_polar(theta="y") +
  facet_grid(.~Group.1, labeller = label_value) + 
  scale_x_discrete(name=" ", breaks = NULL) +
  scale_y_continuous(name=" ", breaks = NULL)
plot(modesplit)

Pie charts good

However when I try to add the labels:

modesplit <- ggplot(data = sums) +
  geom_bar( aes(factor(1),y=x,fill=Group.2),stat="identity", position="fill") +
  geom_text(aes(,y=pos, label = labe), size =5) +
  scale_fill_discrete(guide=guide_legend(title="Mode")) +
  coord_polar(theta="y") +
  facet_grid(.~Group.1,labeller = label_value) +
  scale_x_discrete(name=" ", breaks = NULL) +
  scale_y_continuous(name=" ", breaks = NULL) +
plot(modesplit)

The "pie" of the pie chart vanishes: Bad Pie

I've tried:

Removing the scales
Removing scale_fill_discrete

For some reason your dput structure is not working. can you check if it is exactly the right code? — MichaelVE, May 05 '15 at 05:01
Check: http://stackoverflow.com/questions/29039553/reproducible-example-and-dput-error First ungroup your data — MichaelVE, May 05 '15 at 05:03
I was hoping that grouping might somehow be the problem for my plotting, but no. — raphael, May 05 '15 at 05:14

Gregor Thomas · Accepted Answer · 2015-05-06T00:08:07.003

It's a scale problem. Comment out the coord_polar and your scale_y_continuous, then run the code with and without the geom_text. The position = "fill" in geom_bar makes that add up to 1, whereas your pos values are in the tens of thousands.

Here's a solution (edited so it puts the labels nicely in the middle now)

library(dplyr)
sums2 = sums %>% group_by(Group.1) %>%
    mutate(x_scaled = x / sum(x),
           pos_scaled = pos / cumsum(x_scaled) - x_scaled / 2)

modesplit <- ggplot(data = sums2, aes(x = factor(1))) +
  geom_bar( aes(y=x_scaled, fill=Group.2), stat="identity", position="stack") +
  scale_fill_discrete(guide=guide_legend(title="Mode")) +
  coord_polar(theta="y") +
  geom_text(aes(y = pos_scaled, label = labe), size =5) +
  facet_grid(. ~ Group.1, labeller = label_value) + 
  scale_x_discrete(name=" ", breaks = NULL) +
  scale_y_continuous(name=" ", breaks = NULL)

plot(modesplit)

I accidentally mashed together the two examples without paying too much attention to either it seems. Thanks — raphael, May 06 '15 at 00:16

ggplot's geom_text() labelling of pie chart hides the pie made by geom_bar()

1 Answers1