Introduction
In this chapter, you will learn how to create and customize various types of plots in R using the base R plot() function. The plot() function is versatile and can be used to create a wide range of plots, including scatter plots, line plots, and more. Understanding how to use this function effectively is essential for data visualization in R.
Basic Plotting with plot()
The plot() function can be used to create simple plots quickly. The type of plot created depends on the type of data and the parameters specified.
Scatter Plot
A scatter plot displays points representing the values of two variables.
Example:
# Creating a scatter plot
x <- rnorm(50)
y <- rnorm(50)
plot(x, y, main = "Scatter Plot", xlab = "X-axis", ylab = "Y-axis")
Line Plot
A line plot connects points representing the values of a variable over time or another continuous variable.
Example:
# Creating a line plot
x <- 1:10
y <- x^2
plot(x, y, type = "l", main = "Line Plot", xlab = "X-axis", ylab = "Y-axis")
Scatter Plot with Points and Lines
You can combine points and lines in a single plot.
Example:
# Creating a scatter plot with points and lines
plot(x, y, type = "b", main = "Scatter Plot with Points and Lines", xlab = "X-axis", ylab = "Y-axis")
Customizing Plots
You can customize plots by adding colors, labels, titles, and other graphical parameters.
Adding Colors
Use the col parameter to specify colors for the points or lines.
Example:
# Customizing the plot with colors
plot(x, y, type = "b", col = "blue", main = "Customized Plot", xlab = "X-axis", ylab = "Y-axis")
Adding Titles and Axis Labels
Add main titles, axis labels, and subtitles using the main, xlab, ylab, and sub parameters.
Example:
# Adding titles and axis labels
plot(x, y, type = "b", col = "blue", main = "Customized Plot", xlab = "X-axis", ylab = "Y-axis", sub = "Subtitle")
Adding Legends
Use the legend() function to add a legend to the plot.
Example:
# Adding a legend
plot(x, y, type = "b", col = "blue", main = "Plot with Legend", xlab = "X-axis", ylab = "Y-axis")
legend("topright", legend = "y = x^2", col = "blue", pch = 1, lty = 1)
Multiple Plots
You can add multiple plots to a single graph by using the par() function with the mfrow or mfcol parameters.
Example:
# Creating multiple plots
par(mfrow = c(2, 2)) # 2 rows, 2 columns
plot(x, y, main = "Plot 1")
plot(x, y^2, main = "Plot 2")
plot(x, y^3, main = "Plot 3")
plot(x, y^4, main = "Plot 4")
par(mfrow = c(1, 1)) # Reset to 1 plot
Customizing Points and Lines
You can customize the appearance of points and lines using the pch (plotting character) and lty (line type) parameters.
Example:
# Customizing points and lines
plot(x, y, type = "b", pch = 19, lty = 2, col = "blue", main = "Customized Points and Lines", xlab = "X-axis", ylab = "Y-axis")
Example Program Using plot()
Here is an example program that demonstrates the creation and customization of various plots in R using the base plot() function.
# R Program to Demonstrate Various Plots
# Data for the plots
x <- 1:10
y <- x^2
# Basic scatter plot
plot(x, y, main = "Scatter Plot", xlab = "X-axis", ylab = "Y-axis")
# Line plot
plot(x, y, type = "l", main = "Line Plot", xlab = "X-axis", ylab = "Y-axis")
# Scatter plot with points and lines
plot(x, y, type = "b", main = "Scatter Plot with Points and Lines", xlab = "X-axis", ylab = "Y-axis")
# Customized plot with colors
plot(x, y, type = "b", col = "blue", main = "Customized Plot", xlab = "X-axis", ylab = "Y-axis")
# Adding titles and axis labels
plot(x, y, type = "b", col = "blue", main = "Customized Plot", xlab = "X-axis", ylab = "Y-axis", sub = "Subtitle")
# Adding a legend
plot(x, y, type = "b", col = "blue", main = "Plot with Legend", xlab = "X-axis", ylab = "Y-axis")
legend("topright", legend = "y = x^2", col = "blue", pch = 1, lty = 1)
# Creating multiple plots
par(mfrow = c(2, 2)) # 2 rows, 2 columns
plot(x, y, main = "Plot 1")
plot(x, y^2, main = "Plot 2")
plot(x, y^3, main = "Plot 3")
plot(x, y^4, main = "Plot 4")
par(mfrow = c(1, 1)) # Reset to 1 plot
# Customized points and lines
plot(x, y, type = "b", pch = 19, lty = 2, col = "blue", main = "Customized Points and Lines", xlab = "X-axis", ylab = "Y-axis")
Conclusion
In this chapter, you learned how to create and customize various types of plots in R using the base R plot() function. Plots are essential for data visualization, helping you to understand patterns, trends, and relationships in your data. By mastering the plot() function, you can effectively communicate your data insights through visualizations.