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Adding Text to Plots in R programming – text() and mtext () Function
  • Last Updated : 14 Jul, 2020

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

Syntax: text(x, y, labels)

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 program to add text to plot
# Calling data set
# 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")


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

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

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

Add text to the margins of the graph

mtext() function is used to add text to the margins of the plot.

Syntax: mtext(text, side)

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


# 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)


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

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