arrow(x, y, dx, dy, **kwargs)

Draws arrow on specified axis from (*x*, *y*) to (*x* + *dx*,
*y* + *dy*).

Optional kwargs control the arrow properties:

Constructor arguments

    *length_includes_head*:
       *True* if head is counted in calculating the length.

    *shape*: ['full', 'left', 'right']

    *overhang*:
      distance that the arrow is swept back (0 overhang means
      triangular shape).

    *head_starts_at_zero*:
      If *True*, the head starts being drawn at coordinate 0
      instead of ending at coordinate 0.

Valid kwargs are:
  agg_filter: unknown
  alpha: float or None         

   arrow(x, y, dx, dy, **kwargs)

Draws arrow on specified axis from (*x*, *y*) to (*x* + *dx*,
*y* + *dy*). Uses FancyArrow patch to construct the arrow.

Optional kwargs control the arrow construction and properties:

Constructor arguments
  width: float (default: 0.001)
    width of full arrow tail

  length_includes_head: [True | False] (default: False)
    True if head is to be counted in calculating the length.

  head_width: float or None (default: 3*width)
    total width of the full arrow head

  head_length: float or None (default: 1.5 * head_width)
    length of arrow head

  shape: ['full', 'left', 'right'] (default: 'full')
    draw the left-half, right-half, or full arrow

  overhang: float (default: 0)
    fraction that the arrow is swept back (0 overhang means
    triangular shape). Can be negative or greater than one.

  head_starts_at_zero: [True | False] (default: False)
    if True, the head starts being drawn at coordinate 0
    instead of ending at coordinate 0.

Other valid kwargs (inherited from Patch) are:
  agg_filter: unknown
  alpha: float or None