Introduction to GGPLOT2

This guide introduces users to the ggplot2 R package. Ggplot2 is a popular package that is used to make publication quality graphs in R. The official documentation for the ggplot2 package can be found here. It includes descriptions of functions and sample datasets.

This guide consists of 3 data visualization examples. You can download the code used in this guide here.

Once you have gone over these examples and you feel confident about them, you can test your understanding by trying this activity. If you have any questions, you can request for assistance by filling out our support request form here.

Install package

install.packages("ggplot2")
library(ggplot2)

Example 1: Histogram

data(diamonds)
ggplot(diamonds, aes(price)) + geom_histogram()
ggplot(diamonds, aes(price)) + geom_histogram() + theme_classic()
ggplot(diamonds, aes(price)) + geom_histogram(binwidth=100) + theme_classic()
ggplot(diamonds, aes(price)) + 
  geom_histogram(binwidth=100, fill="darkblue", color="lightblue") + 
  theme_classic() + 
  ggtitle("Histogram of Diamond Prices") + 
  theme(plot.title=element_text(size=20, hjust=0.5)) + 
  xlab("Price") + ylab("Count")
ggsave("histogram1.png")

Histogram of Price of Diamonds

Example 2: Scatterplot

ggplot(diamonds, aes(carat, price)) + geom_point()
ggplot(diamonds, aes(carat, price, colour=clarity)) + 
  geom_point(shape="diamond filled") + 
  theme_light() + 
  ggtitle("Diamond Price by Carat and Clarity")

install.packages("colourpicker")
myscattercolours <- c("#7FFFD4", "#66CDAA", "#458B74", "#00FFFF", "#1C86EE", "#104E8B", "#8B4500", "#FF7F00")

ggplot(diamonds, aes(carat, price, colour=clarity)) + 
  geom_point(shape="diamond filled") + 
  theme_light() + 
  ggtitle("Diamond Price by Carat and Clarity") + 
  scale_colour_manual(values=myscattercolours) +
  xlab("Carat") + ylab("Price") + 
  guides(colour=guide_legend("Clarity"))

Scatterplot of the Price and the Weight of Diamonds

install.packages("RColorBrewer")
library(RColorBrewer)

ggplot(diamonds, aes(carat, price, colour=clarity)) + 
  geom_point(shape="diamond filled") + 
  theme_light() + 
  ggtitle("Diamond Price by Carat and Clarity") + 
  scale_colour_brewer(palette="Blues") +
  xlab("Carat") + ylab("Price") + 
  guides(colour=guide_legend("Clarity"))

Scatterplot of the Price and the Weight of Diamonds

Example 3: Time Series Line Graph

data(economics)
ggplot(economics, aes(x=date, y=uempmed)) +
  theme_minimal() +
  geom_line(colour="yellow3", linewidth=1) + 
  labs(title="US Unemployment Trends",
       subtitle="Median unemployment duration in weeks, 1967–2015") +
  xlab("Date") +
  ylab("Median Duration (Weeks)")

Time Series of Median Unemployment Duration in Weeks

Resources

1. GGPLOT2 Documentation: https://cran.r-project.org/web/packages/ggplot2/ggplot2.pdf
2. GGPLOT2 Tidyverse Reference: https://ggplot2.tidyverse.org/reference/
3. Additional code here.

Technique: Data Visualization | Tools: R