pie chart in ggplot text labelling horror

Question

I can't resolve that strange situation. Somewhere I have error, or bug, but sitting over three halfs of an hour could not deal with it.

I have: sta_df

             sta value
1 IN_LIQUIDATION    29
2     LIQUIDATED    47
3      OPERATING   435
4    TRANSFORMED     8

sp <- ggplot(sta_df, aes(x="", y=value, fill=sta)) +
  geom_bar(width = 1, stat = "identity", color = "black") +
  coord_polar("y") + scale_fill_brewer(palette="Pastel2") +
  geom_text(aes(x = seq(1.2,1.4,,4), label = percent(value/sum(value))), 
                position = position_stack(vjust = 0.5), size=5)

and the plot have wrong direction of labelling.

Nevermind this strange font of a picture. I've tried to use many different functions instead of position_stack. For example:

geom_text(aes(x = rep(seq(0.9,1.4,,6),1), y = value/2 + c(0, cumsum(value)[-length(value)])

but it didn't help. This thread neither: wrong labeling in ggplot pie chart

When I wanted to reverse y=rev(value) the legend didn't correspond with data. Putting direction 1 or -1 doesn't do more than reversing all. Reversing values in geom_text gives Pac-Man-like chart. I've updated ggplot2.

Honestly, the problem is because chart starts to draw anti-clockwise although direction is set to clockwise and text numbers are in right direction. And reversing data in data.frame doesn't change anything in the whole plot. Sorry, I stuck, but feel the solution is right there.

Answer 1

The problem occurs when you assign different x-values to your labels in geom_label(). Why? Because you are relying on position_stack() to give you your y-values. But when the points no longer share the same x, then they don't get 'stacked' anymore. If you want to customize the x-values, you will need to compute your own y-values, as described here (Showing data values on stacked bar chart in ggplot2) and here (http://docs.ggplot2.org/current/geom_text.html) near bottom of the page. By the way, I did all my troubleshooting with coord_polar removed, just looking at the plain barplot version.

Anyway, here is a partial solution:

sta_df <- read.table(header=TRUE,
text="     sta value
IN_LIQUIDATION    29
LIQUIDATED        47
OPERATING        435
TRANSFORMED        8")

library(ggplot2)
library(scales)

sta_df$fraction = sta_df$value / sum(sta_df$value)

sp <- ggplot(sta_df, aes(x="", y=value, fill=sta)) +
      geom_bar(width=1, stat="identity", color="black",) +
      scale_fill_brewer(palette="Pastel2") +
      coord_polar(theta="y") +
      geom_text(aes(x=1.4, label=percent(fraction)), 
                position=position_stack(vjust=0.5), size=4)

ggsave("pie_chart.png", plot=sp, height=4, width=6, dpi=150)