plot.formula              package:base              R Documentation

Formula Notation for Scatterplots

Description:

     Specify a scatterplot or add points or lines via a formula.

Usage:

     plot(formula, data = parent.frame(), ..., subset,
                  ylab = varnames[response], ask = TRUE)
     points(formula, data = parent.frame(), ..., subset)
     lines(formula, data = parent.frame(), ..., subset)

Arguments:

 formula: a `formula', such as `y ~ x'.

    data: a data.frame (or list) from which the variables in `formula'
          should be taken.

     ...: Further graphical parameters may also be passed as arguments,
          see `par'.

  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 `par'.

Details:

     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'. If the formula in
     `plot.formula' contains more than one non-response term, a series
     of plots of y against each term is given. A plot against the
     running index can be specified as `plot(y~1)'.

     If `y' is an object (ie. has a `class' attribute) then
     `plot.formula' looks for a plot method for that class first.

Value:

     These functions are invoked for their side effect of drawing  in
     the active graphics device.

See Also:

     `plot.default', `plot.factor'.

Examples:

     data(airquality)
     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)

