possible bug in quiver

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