ggplot pie chart labeling

Question

I am struggling with getting the pie chart labels correct. Looked around and thought that I could easily implement what mathematicalCoffee did. So far I have this code:

Answer 1

For pie charts plotly works a lot easier than ggplot. Perhaps something like this:

library(plotly)

p <- plot_ly(alloc, labels = ~ltr, values = ~wght, type = 'pie',textposition = 'outside',textinfo = 'label+percent') %>%
  layout(title = 'Letters',
         xaxis = list(showgrid = FALSE, zeroline = FALSE, showticklabels = FALSE),
         yaxis = list(showgrid = FALSE, zeroline = FALSE, showticklabels = FALSE))

Answer 2

We can make it work with ggplot2 and the ggrepel package.

Unfortunately geom_text_repel() does not support a position = argument, so we have to calculate the starting position of the line by hand.

With your data.frame:

alloc$pos = (cumsum(c(0, alloc$wght)) + c(alloc$wght / 2, .01))[1:nrow(alloc)]

This calculates the mean point for each group (or obs, or whtvr you want to call it).

Plugging it in in the geom_text_repel's y aes gives a nice result:

library(ggplot2)
library(ggrepel)
ggplot(alloc, aes(1, wght, fill = ltr)) +
    geom_col(color = 'black', 
             position = position_stack(reverse = TRUE), 
             show.legend = FALSE) +
    geom_text_repel(aes(x = 1.4, y = pos, label = ltr), 
                    nudge_x = .3, 
                    segment.size = .7, 
                    show.legend = FALSE) +
    coord_polar('y') +
    theme_void()

I made some choices, as the use of text instead of label, the removal of the legend and the axes. Feel free to change them