Impossible to draw a direction of arrows in Matplotlib???

Message: 1
Date: Fri, 12 Apr 2013 13:55:32 +0400
From: Bakhtiyor Zokhidov <bakhtiyor_zokhidov@...337...>
Subject: [Matplotlib-users] Impossible to draw a direction of arrows
  in Matplotlib???

I have encountered some problem while I was drawing a direction of
arrow. I have point (x,y) coordinates and angle of them. What I want to
do is that to draw arrow according to the given angle (just to show the
point direction as an arrow in each point coordinate). Here, we should
assume coordinates of '+x', '+y', '-x ', '-y' are 90, 0, 270, 180
degrees, respectively.?
I am a bit unfamiliar with Python drawing tools. I am still not sure to
draw directional point (arrow based on angle) whether I use pylab or
some other modules or.. still not sure at all. I put the following codes
as a sample to give better description:

I see the potential for some confusion over the direction of arrows on a plot here. In standard trigonometry angles of 0, 90, 180, 270 degrees lie along '+x' (1, 0), '+y' (0, 1), '-x' (-1, 0) and '-y' (0, -1). Totally different to what you want. However, this is obviously different to the compass rose.


Dr Andrew Nelson