gapminder-ggplot2-univariate-factor.r

#' ---
#' author: "Jenny Bryan"
#' output: github_document
#' ---

#+ setup, include = FALSE
library(knitr)
opts_chunk$set(fig.path = 'figure/uni-factor-', error = TRUE)

#' Note: this is rendered by applying `knitr::spin()` to an R script. So the
#' narrative is very minimal.



#' load the data and ggplot2 (part of the tidyverse)
library(tidyverse)
library(gapminder)
gapminder

#' bar charts  
#' consider: no. of observations for each continent
table(gapminder$continent)

#' this works because default stat for geom_bar() is "bin"
ggplot(gapminder, aes(x = continent)) + geom_bar()

#' let's reorder the continents based on frequency
p <- ggplot(gapminder, aes(x = reorder(continent, continent, length)))
p + geom_bar()

#' would you rather the bars run horizontally?
p + geom_bar() + coord_flip()

#' how about a better data:ink ratio?
p + geom_bar(width = 0.05) + coord_flip()

#' consider a scenario where you DON'T want the default "bin" stat, i.e. the bar
#' length or height already exists as a variable
(continent_freq <- gapminder %>% count(continent))

#' this simple call no longer works, because we have pre-tabulated
ggplot(continent_freq, aes(x = continent)) + geom_bar()

#' THIS works when bar length or height already exists
ggplot(continent_freq, aes(x = continent, y = n)) + geom_bar(stat = "identity")

sessionInfo()