# Add text to a plot in R software

To add a text to a plot in R, the text() and mtext() R functions can be used.

# Add texts within the graph

The text() function can be used to draw text inside the plotting area. A simplified format of the function is :

``text(x, y, labels)``
• x and y: numeric vectors specifying the coordinates of the text to plot
• labels: a character vector indicating the text to be written

An example is shown below :

``````d<-head(mtcars)
plot(d[,'wt'], d[,'mpg'],
main="Milage vs. Car Weight\n~~~~~~~~~~~~~~~~~~~",
xlab="Weight", ylab="Miles/(US) gallon",
pch=19, col="darkgreen")
text(d[,'wt'], d[,'mpg'],  row.names(d),
cex=0.65, pos=3,col="red") `````` # Add text in the margins of the graph

The mtext() R function can be used to put a text in one of the four margins of the plot. A simplified format of the function is :

``mtext(text, side=3)``
• text : the text to be written
• side : an integer specifying the side of the plot; Possible values are :
• 1: bottom
• 2: left
• 3: top
• 4: right

An example is shown below :

``````plot(1:10, 1:10,
main="mtext(...) examples\n~~~~~~~~~~~")
mtext("Magic function", side=3)`````` # Add mathematical annotation to a plot

``````plot(1:10, 1:10,
main="text(...) examples\n~~~~~~~~~~~")
text(4, 9, expression(hat(beta) == (X^t * X)^{-1} * X^t * y))
text(7, 4, expression(bar(x) == sum(frac(x[i], n), i==1, n)))`````` # Infos

This analysis has been performed using R statistical software (ver. 3.1.0).