.BG
.FN identify
.TL
Identify Points on Plot
.CS
identify(x, y, labels=seq(along=x), n=length(x),
         plot=T, atpen=T, offset=.5)
.XY
.NA
.AG labels
optional vector giving labels for each of the points.
If supplied, must have the same length as `x' and `y'.
.AG n
maximum number of points to identify.
.AG plot
if `TRUE', `identify' plots the labels of
the points identified. In any case, the subscripts are
returned.
.AG atpen
if `TRUE', plotted identification is
relative to locator position when point is identified;
otherwise, plotting is relative to the identified `x,y' value.
Useful for controlling position of labels when points are
crowded.
.AG offset
identification is plotted as a text string, moved `offset'
character widths from the point.  If the locator was
left (right) of the nearest point, the label will be offset
to the left (right) of the point.
.GR
.RT
indices (in `x' and `y') corresponding to identified points.
.PP
See the documentation for the specific
graphics device for details on graphical input techniques.
.PP
The nearest point to locator position is identified, but must be at most
0.5 inches away.
In case of ties, the earliest point is identified.
.EX
identify(x,y,z)   # plot z values when x,y points identified

bad <- identify(x,y,plot=FALSE)
xgood <- x[-bad]       #eliminate identified "bad" points
ygood <- y[-bad]         #from x and y
.KW iplot
.KW dplot
.KW aplot
.WR
