Re: [matplotlib-devel] possible bug in quiver

[David R. <ra...@ke...>]

Eric,

OK, that seems to work.  I tried something with scale_units earlier
without success, but I must have been doing something wrong.

Thanks for the help.

Dave

 > On 2012/08/29 10:07 AM, David Raymond wrote:
 > >
 > > I think that I have found a serious bug in vector plotting (quiver)
 > > when the "angle=xy" option is used on a plot with a large aspect
 > > ratio.  It is my understanding that with this option, the vector with
 > > tail at (x,y) would have its head at (x + vx,y + vy); at least this is
 > > what it says in the documentation.
 > 
 > Not a bug.
 > Note this in the documentation:
 > 
 >    *scale_units*: *None*, or any of the *units* options.
 >      For example, if *scale_units* is 'inches', *scale* is 2.0, and
 >      ``(u,v) = (1,0)``, then the vector will be 0.5 inches long.
 >      If *scale_units* is 'width', then the vector will be half the width
 >      of the axes.
 > 
 >      If *scale_units* is 'x' then the vector will be 0.5 x-axis
 >      units.  To plot vectors in the x-y plane, with u and v having
 >      the same units as x and y, use
 >      "angles='xy', scale_units='xy', scale=1".
 > 
 > Try this modified call to quiver:
 > 
 > q = plt.quiver(X, Y, vx, vy, angles='xy', scale_units='xy')
 > 
 > Eric