pie chart in ggplot2

README.md

Here I'll drop ggplot2 tricks ...

Table of Contents:

• piechart.R: getting the order of the colors right is quite a task
• themes.R: ggthemes is really useful

cheat_sheet.R

# percentage formatting
scale_x_continuous(labels = percent_format())

# Remove legend for a particular aesthetic (fill)
bp + guides(fill=FALSE)

# It can also be done when specifying the scale
bp + scale_fill_discrete(guide=FALSE)

# This removes all legends
bp + theme(legend.position="none")

piechart.R

library(ggplot2)
library(ggthemes)

nb_by_activity <- structure(list(Interactions = c(1337266L, 98415L, 71079L, 537486L, 
56709L), InteractionDays = c(51362L, 26480L, 26061L, 24686L, 
18948L), activity_name = structure(c(1L, 3L, 4L, 2L, 5L), .Label = c("task 1", 
"task 4", "task 2", "task 3", "task 5"), class = "factor")), .Names = c("Interactions", 
"InteractionDays", "activity_name"), row.names = c(NA, 5L), class = "data.frame")

#' to watch for:
#' to get the order of the legend right and chart right, we need multiple actions:
#' 1. correct factor order
#' 2. setting the order in aes()
#' 3. setting reverse order in coord_polar

nb_by_activity$activity_name <- factor(nb_by_activity$activity_name, 
                                       levels = nb_by_activity$activity_name[order(nb_by_activity$Interactions, decreasing=TRUE)])

activity_pie_chart <- 
  ggplot(nb_by_activity, aes(x = factor(1), fill = factor(activity_name), y = (Interactions)/sum(Interactions),
                             order = (Interactions)/sum(Interactions))) +
  geom_bar(stat = "identity", width = 1) + 
  labs(title = sprintf("Number of Interactions by activity"), x = "", y= "") + 
  getstyle(15) + scale_fill_tableau("colorblind10")+
  coord_polar(theta="y", direction = -1) +
  theme(legend.position="right") +
  theme(axis.text.y = element_blank(), axis.text.x = element_blank(), 
        legend.text=element_text(size=14), legend.title=element_text(size=14) )+
  guides(fill = guide_legend(title = "Activity"))
plot(activity_pie_chart)

themes.R

#' check also: https://github.com/jrnold/ggthemes
#' (especially for the color schemes)

#' define style for the charts ####
#' usage: g <- g +getstyle (20)
getstyle <- function(text_size = 20){
  theme_bw() +
  theme(axis.title.x = element_text(colour="black", size=text_size)) +
  theme(axis.text.x = element_text(size = text_size)) +
  theme(axis.title.y = element_text(colour="black", size=text_size)) +
  theme(axis.text.y = element_text(size = text_size)) +
  theme(legend.position="none") +
  theme(plot.title = element_text(face="bold", size = text_size+2, vjust = 2)) 
}