Adding Text to Plots in R programming – text() and mtext () Function

Text is defined as a way to describe data related to graphical representation. They work as labels to any pictorial or graphical representation. In this article, we will learn to add a text to a plot in R Programming Language by using the text() and mtext() functions.

R – text () Function

text () Function in R Programming Language is used to draw text elements to plots in Base R.

Syntax: text(x, y, labels)

Parameters:

• x and y: numeric values specifying the coordinates of the text to plot
• labels: the text to be written

Returns: Added text to plot 

Example 1:

R

# R program to add text to plot

# Calling data set
d<-head(mtcars)

# Plotting the graph
plot(d[, 'wt'], d[, 'mpg'],
     main = " Car Weight vs. Milage ",
     xlab = "Miles", ylab = " Weight",
     pch = 19, col = "darkgreen")

# Calling text() function
text(d[, 'wt'], d[, 'mpg'],  row.names(d),
     cex = 0.88, pos = 2, col = "darkgreen")

Output:

In the above example, the text is added to the plot of ‘mtcar’ dataset.

Example 2: Implementation of text() to add a mathematical annotation to a plot 

R

# R program to add text to plot

# Plotting the graph
plot(1:5, 1:5,
     main = "text() Function  examples")

# Calling text() function
text(2, 3, expression(hat(beta) == (X^t * X)^{-1} * X^t * y))
text(3, 4, expression(bar(x) == sum(frac(x[i], n), i==1, n)))

Output:

In the above example, the text() function is used to add a mathematical annotation to a plot

R – mtext () Function to Add text to the margins of the graph

mtext() function in R Programming Language is used to add text to the margins of the plot. 

Syntax: mtext(text, side)

Parameters:

• text: text to be written
• side: An integer specifying the side of the plot, such as: bottom, left, top, and right.

Returns: Added text in the margins of the graph 

Example:

R

# R program to add text to a plot

# Creating a plot
plot(1:5, 1:5,
     main = "mtext examples")

# Calling mtext() function
mtext("mtext() function", side = 3)

Output:

Here, in the above example, the side specifies the side of the plot such as the bottom, left, top, right. And in the given the side=3 i.e the top part of the plot.