| abline {graphics} | R Documentation |
This function adds one or more straight lines through the current plot.
abline(a = NULL, b = NULL, h = NULL, v = NULL, reg = NULL,
coef = NULL, untf = FALSE, ...)
a, b |
the intercept and slope, single values. |
untf |
logical asking whether to untransform. See Details. |
h |
the y-value(s) for horizontal line(s). |
v |
the x-value(s) for vertical line(s). |
coef |
a vector of length two giving the intercept and slope. |
reg |
an object with a coef method. See Details. |
... |
graphical parameters such as
col, lty and lwd (possibly as vectors: see
Details) and the line characteristics lend, ljoin and
lmitre. |
Typical usages are
abline(a, b, untf = FALSE, ...) abline(h=, untf = FALSE, ...) abline(v=, untf = FALSE, ...) abline(coef=, untf = FALSE, ...) abline(reg=, untf = FALSE, ...)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 with a coef method.
If this returns a vector 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 always refer to original coordinates.
The graphical parameters col, lty and lwd
can be specified; see par for details. For the
h= and v= usages they can be vectors of length greater
than one, recycled as necessary.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Murrell, P. (2005) R Graphics. Chapman & Hall/CRC Press.
lines and segments for connected and
arbitrary lines given by their endpoints.
par.
## Setup up coordinate system (with x==y aspect ratio): plot(c(-2,3), c(-1,5), type = "n", xlab="x", ylab="y", asp = 1) ## the x- and y-axis, and an integer grid abline(h=0, v=0, col = "gray60") text(1,0, "abline( h = 0 )", col = "gray60", adj = c(0, -.1)) abline(h = -1:5, v = -2:3, col = "lightgray", lty=3) abline(a=1, b=2, col = 2) text(1,3, "abline( 1, 2 )", col=2, adj=c(-.1,-.1)) ## Simple Regression Lines: sale5 <- c(6, 4, 9, 7, 6, 12, 8, 10, 9, 13) plot(sale5) abline(lsfit(1:10,sale5)) abline(lsfit(1:10,sale5, intercept = FALSE), col= 4) # less fitting z <- lm(dist ~ speed, data = cars) plot(cars) abline(z) # equivalent to abline(reg = z) or abline(coef = coef(z)) ## trivial intercept model abline(mC <- lm(dist ~ 1, data = cars)) ## the same as abline(a = coef(mC), b = 0, col = "blue")