ggplot_forcats.rmd

---
title: 'tidyverse: using forcats to improve your ggplots'
author: "catlin"
date: "2/10/2021"
output: html_document
---

Note that although forcats is part of the "tidyverse", it is not automatically loaded when you run `library(tidyverse)`

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

library(tidyverse)
library(forcats)
```

# Handy forcats functions for ggplot2

## Comparing followers of world religions

Source: https://en.wikipedia.org/wiki/List_of_religious_populations

I was looking for a simple dataset with count data for many items to demonstrate some basic forcats functions that are useful when creating plots.

```{r, warning=FALSE}
religions = read_csv("https://raw.githubusercontent.com/acatlin/data/master/religions.csv", 
                  col_names = FALSE) %>% 
    rename(religion = X1, followers = X2) %>% 
    mutate(millions_of_followers = followers/1000000.0) %>% 
  select(religion, millions_of_followers)

religions
```

## 1A: basic ggplot

Q: What are the most followed religions?
A: Use ggplot to compare religious populations

You can also embed plots, for example:

```{r}
religions %>% 
  ggplot(aes(x = religion, y = millions_of_followers)) + 
    geom_col(fill = "lightblue") + 
    labs(x = "religion", y = "millions of followers", 
           caption = "https://en.wikipedia.org/wiki/List_of_religious_populations") 
```
 
## 1B: How do I flip coordinates?

```{r}
religions %>% 
  ggplot(aes(x = religion, y = millions_of_followers)) + 
    geom_col(fill = "lightblue") + 
    labs(x = "religion", y = "millions of followers", 
           caption = "https://en.wikipedia.org/wiki/List_of_religious_populations") + coord_flip()
```

## 2A: How do I change sort order?
Revised by: Andy Catlin

Q: How do we change the chart to show the most followed religions first?
A: Use forcats::fct_reorder()

```{r}
library(forcats) 

ggplot(religions, aes(x = fct_reorder(religion, millions_of_followers), 
                      y = millions_of_followers)) + 
  geom_col(fill = "lightblue") + 
  labs(x = "religion", y = "millions of followers", 
      caption = "https://en.wikipedia.org/wiki/List_of_religious_populations") + 
  coord_flip()
```

## 2B: How do I combine less frequently used categories?

Q: How do we combine the less-followed religions into a single group?
A: Use forcats::fct_other()

```{r}
top5 = unlist(select(head(arrange(religions, desc(millions_of_followers)), 5), religion))

religions %>% 
  mutate(religion = fct_other(religion, keep = top5, other_level = "Other religions")) %>%     
  ggplot(aes(x = fct_reorder(religion, millions_of_followers), y = millions_of_followers)) +
    geom_col(fill = "lightblue") + 
    labs(x = "religion", y = "millions of followers", 
        caption = "https://en.wikipedia.org/wiki/List_of_religious_populations") + 
        coord_flip()
```