

   IIddeennttiiffyy PPooiinnttss iinn aa SSccaatttteerr PPlloott

        identify(x, y = NULL, labels = seq(along = x), pos = FALSE,
                 n = length(x), plot = TRUE, offset = 0.5, ...)

   AArrgguummeennttss::

        x,y: coodinates of points in a scatter plot.  Alterna-
             tively, any object which can defines coordinates
             (a plotting structure, time series etc.) can be
             given as `x' and `y' left undefined.

     labels: an optional vector, the same length as `x' and
             `y', giving labels for the points.

        pos: if `pos' is `TRUE', a component is added to the
             return value which indicates where text was plot-
             ted relative to each identified point (1=below,
             2=left, 3=above and 4=right).

          n: the maximum number of points to be identified.
             (Not yet implemented.)

       plot: if `plot' is `TRUE', the labels are printed at the
             points and if `FALSE' they are omitted.  (Not yet
             implemented.)

     offset: the distance (in character widths) which separates
             the label from identified points.  (Not yet imple-
             mented.)

        ...: further arguments to `par(.)'.

   DDeessccrriippttiioonn::

        This function reads the position of the graphics
        pointer when the (first) mouse button is pressed.  It
        then searches the coordinates given in `x' and `y' for
        the point closest to the pointer.  If this point is
        close to the pointer, its index will be returned as
        part of the value of the call.

        The following, and the `n', `ploy' and `offset' argu-
        ments are not yet implented: If in addition, `plot' is
        `TRUE' the point is labelled with the corresponding
        element of `text'.

        The labels are placed either below, to the left, above
        or to the right of the identified point, depending on
        where the cursor was.

        The identification process is terminated by pressing
        any mouse button other than the first, or by clicking
        outside the graphics window.

   VVaalluuee::

        If `pos' is `FALSE', `identify' returns an integer vec-
        tor containing the indexes of the identified points.
        If `pos' is `TRUE', `identify' returns a list contain-
        ing a component `ind', indicating which points were an
        identified and a component `pos', indicating where the
        labels were placed relative to the identified points.

