This help topic is for R version 1.5.0. For the current version of R, try https://stat.ethz.ch/R-manual/R-patched/library/base/html/abline.html
abline {base}R Documentation

Add a Straight Line to a Plot

Description

This function adds one or more straight lines through the current plot.

Usage

abline(a, b, untf = FALSE, ...)
abline(h=, untf = FALSE, ...)
abline(v=, untf = FALSE, ...)
abline(coef=, untf = FALSE, ...)
abline(reg=, untf = FALSE, ...)

Arguments

a, b

the intercept and slope.

untf

logical. See Details.

h

the y-value for a horizontal line.

v

the x-value for a vertical line.

coef

a vector of length two giving the intercept and slope.

reg

an object with a coef component. See Details.

...

graphical parameters.

Details

The first form specifies the line in intercept/slope form (alternatively a can be specified on its own and is taken to contain the slope and intercept in vector form).

The h= and v= forms draw horizontal and vertical lines at the specified coordinates.

The coef form specifies the line by a vector containing the slope and intercept.

reg is a regression object which contains reg$coef. If it is of length 1 then the value is taken to be the slope of a line through the origin, otherwise, the first 2 values are taken to be the intercept and slope.

If untf is true, and one or both axes are log-transformed, then a curve is drawn corresponding to a line in original coordinates, otherwise a line is drawn in the transformed coordinate system. The h and v parameters alway refer to original coordinates.

The graphical parameters col and lty can be specified as arguments to abline; see par for details.

See Also

lines and segments for connected and arbitrary lines given by their endpoints. par.

Examples

data(cars)
z <- lm(dist ~ speed, data = cars)
plot(cars)
abline(z)

[Package base version 1.5.0 ]