ggarrow 0.1.0

Initial CRAN submission

Geom layers

Several geom functions:

• geom_arrow() that works like geom_path().
• geom_arrow_segment() that works like geom_segment()
• geom_arrow_chain() that works like a type = "b" plot from base R.
• geom_arrow_curve() that works like geom_curve().

Arrow grob

The function grob_arrow() creates a grid grob that largely mimics the
polylineGrob() grob, with the following differences.

• Arrow ornaments can be placed at the end, start or middle of the line.
  • arrow_{head/fins/mid} controls the shape of the ornament.
  • length_{head/fins/mid} controls the size of the ornament.
  • justify controls where an ornament is placed relative to the line ends.
  • mid_place controls where middle (interior) arrows are placed.
  • resect{_head/_fins} can shorten the endpoints.
  • force_arrow determines if arrows are drawn on lines that are too short
    to accommodate ornaments.
• The linewidth of the line can vary within a line.
  • shaft_width controls the linewidth for every point in x and y
• A line can be shortened from their endpoints using the resect{_head/_fins}
  arguments.
• The line is treated as a polygon, so fill controls the colour of the line,
  whereas colour controls the colour of an outline.

Arrow scales

The arrow_{head/fins/mid} have been promoted from parameters to aesthetics.
Correspondingly, there are now 3 discrete scales for these 3 aesthetics.

Arrow shapes

Added the following shapes for ornaments:

• arrow_head_wings() that looks like a classic arrow.
• arrow_head_line() that are two line protruding from the tip of the line.
• arrow_head_minimal() that is just a stumpy line-end.
• arrow_fins_feather() two stacked parallelograms.
• arrow_fins_line() also two lines but in opposite direction.
• arrow_fins_minimal() that is just a line-end with a triangle taken out.
• arrow_cup() that forms an arc around a point.

Other

An annotate_arrow() layer to specifically do arrow annotations.
An element_arrow() to replace line elements in the theme() by arrows.