| plot.formula {graphics} | R Documentation |
Formula Notation for Scatterplots
Description
Specify a scatterplot or add points, lines, or text via a formula.
Usage
## S3 method for class 'formula'
plot(formula, data = parent.frame(), ..., subset,
ylab = varnames[response], ask = dev.interactive())
## S3 method for class 'formula'
points(formula, data = parent.frame(), ..., subset)
## S3 method for class 'formula'
lines(formula, data = parent.frame(), ..., subset)
## S3 method for class 'formula'
text(formula, data = parent.frame(), ..., subset)
Arguments
formula |
a |
data |
a data.frame (or list) from which the variables in
|
... |
Arguments to be passed to or from other methods.
|
subset |
an optional vector specifying a subset of observations to be used in the fitting process. |
ylab |
the y label of the plot(s). |
ask |
logical, see |
Details
For the lines, points and text methods the formula
should be of the form y ~ x or y ~ 1 with a left-hand
side and a single term on the right-hand side. The plot method
accepts other forms discussed later in this section.
Both the terms in the formula and the ... arguments are
evaluated in data enclosed in parent.frame() if
data is a list or a data frame. The terms of the formula and
those arguments in ... that are of the same length as
data are subjected to the subsetting specified in
subset. A plot against the running index can be specified as
plot(y ~ 1).
If the formula in the plot method contains more than one term
on the right-hand side, a series of plots is produced of the response
against each non-response term.
For the plot method the formula can be of the form
~ z + y + z: the variables specified on the right-hand side are
collected into a data frame, subsetted if specified, and displayed by
plot.data.frame.
Missing values are not considered in these methods, and in particular cases with missing values are not removed.
If y is an object (i.e., has a class attribute)
then plot.formula looks for a plot method for that class first.
Otherwise, the class of x will determine the type of the plot.
For factors this will be a parallel boxplot, and argument
horizontal = TRUE can be specified (see boxplot).
Note that some arguments will need to be protected from premature
evaluation by enclosing them in quote: currently this is
done automatically for main, sub and xlab. For
example, it is needed for the panel.first and panel.last
arguments passed to plot.default.
Value
These functions are invoked for their side effect of drawing on the active graphics device.
See Also
plot.default, points, lines,
plot.factor.
Examples
op <- par(mfrow = c(2,1))
plot(Ozone ~ Wind, data = airquality, pch = as.character(Month))
plot(Ozone ~ Wind, data = airquality, pch = as.character(Month),
subset = Month != 7)
par(op)
## text.formula() can be very natural:
wb <- within(warpbreaks, {
time <- seq_along(breaks); W.T <- wool:tension })
plot(breaks ~ time, data = wb, type = "b")
text(breaks ~ time, data = wb, labels = W.T, col = 1+as.integer(wool))