What is the ggplot2 package in R?

Key takeaways:

  • The ggplot2 library in R is a widely used tool that offers customization and aesthetics, adhering to the principles of the “Grammar of Graphics.”

  • Built-in datasets in R allow users to experiment easily, facilitating practice and learning as they explore various data visualization techniques.

  • Installation of ggplot2 can be done through the tidyverse package or directly using the ggplot2 library.

  • The ggplot() function is the foundation for creating plots, combining data and aesthetics while enabling various geometric functions for different charts.

  • ggplot2 has functions to create various plots, such as scatter plots, line graphs, and box plots, enabling effective data visualization.

R language and data visualization

In today’s data-driven world, effective data visualization is crucial for understanding complex information. R is widely used by statisticians and data scientists for handling statistical analyses, complex calculations, and data visualization. With numerous specialized libraries like ggplot2, it offers powerful tools that simplify the process of learning and creating visual representations of data. It also has built-in datasets that can be used for experimenting and learning.

The ggplot2 package in R

Among the many libraries of R, the ggplot2 is one of the most popular libraries, and it stands out as a versatile tool that embodies the principles of the “Grammar of Graphics,”The Grammar of Graphics is a way to build visualizations by layering simple components like data, shapes, and scales to create complex visuals. making it easier to create informative and aesthetic charts. The ggplot2 is considered versatile because it allows for easy customization since we add the plot’s aesthetics layer by layer.

How to install and use the ggplot2 package

Installation

There are two ways to install ggplot2:

  1. We can use the tidyverse library. The ggplot2 package is contained within the tidyverse library, so installing it automatically installs ggplot2.

install.packages("tidyverse")
library(tidyverse)
Installing ggplot2 vis tidyverse

  1. We can directly use the ggplot2 library.

install.packages("ggplot2")
library(ggplot2)
Installing ggplot2 on its own

Implementation

After we install and load the library, using either of the options shown above, the next step is to use the package.

We’ll need to invoke the ggplot() function for this.

Syntax for the ggplot function

ggplot(data = <DATA>, mapping = aes(<MAPPINGS>)) +  <GEOM_FUNCTION>()
The ggplot function in R

Let’s understand this ggplot() function call:

  • The function ggplot() wraps together the data and the aesthetics needed.

  • The argument data specifies the data file being used.

  • The mapping specifies the variables being used to build the chart. These are x and y variables where needed.

  • The <GEOM_FUNCTION> can be any function, such as geom_point for scatterplots, geom_line for line plots or even geom_boxplot for boxplots.

Code example

Let’s look at the code below. Here, we’ll analyze the iris dataset by creating a scatter plot that displays the correlation of sepal width and length :

library(tidyverse)
ggplot(data = iris, 
     mapping = aes(x = Sepal.Length, y = Sepal.Width)) +
     geom_point() +
     ggtitle("Sepal Width Vs Sepal Length") +
     theme(plot.title = element_text(hjust = 0.5)) +
     xlab("Length") +
     ylab("Width")

Code explanation

Here is a line-by-line explanation of the code:

  • Line 1: We load the tidyverse library. The ggplot2 can also be used here instead.

  • Line 2–4: We plot the iris data, sepal length, and width using the geom_point().

  • Line 5: We add a title to the plot using ggtitle().

  • Line 6: We center the title since, by default, the title is left_aligned.

  • Lines 7 and 8: We add labels on the x- and y-axes.

Note: We can access the built-in datasets and their descriptions using the data() function.

Conclusion

Effective data visualization makes complex information understandable and comprehendible and thus enables you to draw clearer insights from complex datasets and facilitates data-driven decision-making. Whether you’re a beginner or an experienced analyst, learning to use the ggplot2 package in R equips you with powerful tools for effective data storytelling.

Want to gain hands-on experience in R data visualization? Engage in practical projects from Educative.io, such as the Uber Data Analysis project, which focuses on analyzing and visualizing Uber data for New York City, and the Stock Market Data Analysis project, which explores stock market trends using ggplot2.

Frequently asked questions

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What is ggplot2 in R?

ggplot2 is a popular package in R for creating visualizations, such as charts and graphs, to help us understand data better.

How do I install ggplot2 package in R?

You can install ggplot2 in R by running the command install.packages("ggplot2"), and then load it with library(ggplot2). The second option is to install ggplot2's parent package using the command install.packages("tidyverse") and then load it with library(tidyverse).

Is ggplot a function or a package?

In R language, ggplot is a function within the ggplot2 package that helps you create plots by combining data and visual elements.

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