\HeaderA{grid.segments}{Draw Line Segments}{grid.segments}
\aliasA{segmentsGrob}{grid.segments}{segmentsGrob}
\keyword{dplot}{grid.segments}
\begin{Description}\relax
These functions create and draw line segments.
\end{Description}
\begin{Usage}
\begin{verbatim}
grid.segments(x0 = unit(0, "npc"), y0 = unit(0, "npc"),
              x1 = unit(1, "npc"), y1 = unit(1, "npc"),
              default.units = "npc", units.per.obs = FALSE,
              arrow = NULL,
              name = NULL, gp = gpar(), draw = TRUE, vp = NULL)
segmentsGrob(x0 = unit(0, "npc"), y0 = unit(0, "npc"),
              x1 = unit(1, "npc"), y1 = unit(1, "npc"),
              default.units = "npc", units.per.obs = FALSE,
              arrow = NULL, name = NULL, gp = gpar(), vp = NULL)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x0}] Numeric indicating the starting x-values of the line segments. 
\item[\code{y0}] Numeric indicating the starting y-values of the line
segments. 
\item[\code{x1}] Numeric indicating the stopping x-values of the line
segments. 
\item[\code{y1}] Numeric indicating the stopping y-values of the line segments.
\item[\code{default.units}] A string. 
\item[\code{units.per.obs}] A boolean indicating whether distinct units are
given for each x/y-value. 
\item[\code{arrow}] A list describing arrow heads to place at either end
of the line segments, as produced by the \code{arrow} function.
\item[\code{name}] A character identifier. 
\item[\code{gp}] An object of class \code{gpar}. 
\item[\code{draw}] A logical value indicating whether graphics output
should be produced.
\item[\code{vp}] A Grid viewport object (or NULL)
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
Both functions create a segments grob (a graphical object describing
segments), but only \code{grid.segments}
draws the segments (and then only if \code{draw} is \code{TRUE}).
\end{Details}
\begin{Value}
A segments grob.  \code{grid.segments} returns the value invisibly.
\end{Value}
\begin{Author}\relax
Paul Murrell
\end{Author}
\begin{SeeAlso}\relax
\LinkA{Grid}{Grid},
\code{\LinkA{viewport}{viewport}},
\code{\LinkA{arrow}{arrow}}
\end{SeeAlso}

