Adding Straight Lines to a Plot in R Programming – abline() Function
abline() function in R Language is used to add one or more straight lines to a graph. The
abline() function can be used to add vertical, horizontal or regression lines to plot.
abline(a=NULL, b=NULL, h=NULL, v=NULL, …)
a, b: It specifies the intercept and the slope of the line
h: specifies y-value for horizontal line(s)
v: specifies x-value(s) for vertical line(s)
Returns: a straight line in the plot
Example 1: To add a vertical line to the plot
Here, in above example straight line is added using abline() to different graphical plots
Example 2: To add a horizontal line
In above example
abline() Function draws an horizontal line on the current plot at the specified ‘x’ coordinates.
Example 3: To add a regression line
In the above example, straight-line is added using the line equation and
abline() function and plot relation between speed and distance.