Re: [Matplotlib-users] Re: How to draw an arrow using matplotlib

[John H. <jdh...@ac...>]

>>>>> "Chris" == Chris  <bi...@Fu...> writes:

    Chris> I tried with what you suggested to make an Arrow class. To
    Chris> begin with, I only put an Line2D instance. I searched for
    Chris> table stuff in axes.py, matlab.py to make the arrow
    Chris> importable from matplotlib.matlab. Then I also try a very
    Chris> very simple demo and I expect to see a simple
    Chris> line. However, I can not see it. Could someone tell me what
    Chris> is the problem. Here is my very very rudimental codes.

Nowhere in your code do you actually draw the arrows in self.arrows.
In Axes.draw you would need to do

    for arrow in self.arrows: 
        arrow.draw(renderer)

And this should work.

However, you can avoid all the overhead of add_arrow, and keeping a
list of arrows in self.arrows simply by doing


     def arrow(self, x, y, *args, **kwargs):
         a = Arrow(x,y, *args, **kwargs)
         self.add_artist(a)
                 ^^^
         return a

Ie, call add_artist which is a generic method for adding artists to
the axes.

Hope this helps,
JDH