set style arrow

You can use set style arrow to define a set of arrow types. Each type has its own width, point type, color, etc so that you can refer to them later by an index instead of repeating all the information at each invocation.

Syntax:

      set style arrow <index> default
      set style arrow <index> {nohead | head | backhead | heads}
                              {size <length>,<angle>{,<backangle>} {fixed}}
                              {filled | empty | nofilled | noborder}
                              {front | back}
                              { {linestyle | ls <line_style>}
                                | {linetype | lt <line_type>}
                                  {linewidth | lw <line_width}
                                  {linecolor | lc <colorspec>}
                                  {dashtype | dt <dashtype>} }
      unset style arrow
      show style arrow

<index> is an integer that identifies the arrowstyle.

If default is given all arrow style parameters are set to their default values.

If the linestyle <index> already exists, only the given parameters are changed while all others are preserved. If not, all undefined values are set to the default values.

An arrow style invoked from a plot or splot command can include a data-dependent linecolor (lc variable or lc rgb variable) that consumes an additional column of data in the corresponding using specification. In this case the style is probably not useful for individual arrows created by set arrow.

Specifying nohead produces arrows drawn without a head---a line segment. This gives you yet another way to draw a line segment on the plot. By default, arrows have one head. Specifying heads draws arrow heads on both ends of the line.

Head size can be modified using size <length>,<angle> or size <length>,<angle>,<backangle>, where <length> defines length of each branch of the arrow head and <angle> the angle (in degrees) they make with the arrow. <Length> is in x-axis units; this can be changed by first, second, graph, screen, or character before the <length>; see coordinates for details.

By default the size of the arrow head is reduced for very short arrows. This can be disabled using the fixed keyword after the size command.

<backangle> is the angle (in degrees) the back branches make with the arrow (in the same direction as <angle>). It is ignored if the style is nofilled.

Specifying filled produces filled arrow heads with a border line around the arrow head. Specifying noborder produces filled arrow heads with no border. In this case the tip of the arrow head lies exactly on the endpoint of the vector and the arrow head is slightly smaller overall. Dashed arrows should always use noborder, since a dashed border is ugly. Not all terminals support filled arrow heads.

The line style may be selected from a user-defined list of line styles (see set style line) or may be defined here by providing values for <line_type> (an index from the default list of styles) and/or <line_width> (which is a multiplier for the default width).

Note, however, that if a user-defined line style has been selected, its properties (type and width) cannot be altered merely by issuing another set style arrow command with the appropriate index and lt or lw.

If front is given, the arrows are written on top of the graphed data. If back is given (the default), the arrow is written underneath the graphed data. Using front will prevent a arrow from being obscured by dense data.

Examples:

To draw an arrow without an arrow head and double width, use:

      set style arrow 1 nohead lw 2
      set arrow arrowstyle 1

See also set arrow for further examples.