Re: [Matplotlib-users] Impossible to draw a direction of arrows in Matplotlib???

[Ryan N. <rne...@gm...>]

I'm not sure that I understand exactly what you are trying to do, but 
you may want to look into Matplotlib annotation. Here's a really quick 
example:

import matplotlib.pyplot as plt
plt.annotate('', (1, 1), (0, 0),
         arrowprops=dict(facecolor='black'))
plt.axis([-1, 2, -1, 2])
plt.show()

There are many options to make very fancy arrows, and there are several 
places in the docs to read about this in more detail:
http://matplotlib.org/users/annotations_intro.html
http://matplotlib.org/users/annotations_guide.html

Hope that helps a little. Good luck.

Ryan

On 4/12/2013 5:55 AM, Bakhtiyor Zokhidov wrote:
> Hi,
> 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:
>
> import numpy as np
> import scipy as sp
> import pylab as pl
>
>
> def draw_line(x,y,angle):
>      # Inputs:
>      x = np.array([ 2, 4, 8, 10, 12, 14, 16])
> y = np.array([ 5, 10, 15, 20, 25, 30, 35])
> angles = np.array([45,275,190,100,280,18,45])
>
> # First, draw (x,y) coordinate
> ???
> # Second, according to the angle indicate the direction as
> an arrow
> ???
>
> Thanks in advance for your friendly support,
>
>
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