On Tue, Jan 3, 2012 at 11:57 AM, Mario Fuest wrote:
Hi,

Maybe a bad idea to ask a question on x-mas. Well, I hope it’s not that
unpolite to push one‘s questions. :)

Basically I just want to set a fixed width/height on my figure. That
should be possible?

Mario Fuest <mariofuest@aol.com> schrieb am Sat, 24. Dec 16:42:
> Hi there,
>
> I want to examine a vector field and therefore i used "quiver" to
> visualize said field:
>
> > import numpy as np
> > import matplotlib.pyplot as plt
> >
> > # points
> > x, y = np.meshgrid(np.arange(0, 2*np.pi, 0.1),
> >                    np.arange(0, 1*np.pi, 0.1))
> > # derivatives
> > dx = -2*np.sin(x)*np.cos(y)
> > dy =    np.cos(x)*np.sin(y)
> >
> > # plot
> > plt.figure()
> > plt.quiver(dx, dy, color='b')
> >
> > # beautiful axis
> > a = plt.gca()
> > x_a, y_a = a.get_xaxis(), a.get_yaxis()
> > a.axis('tight')
> > # TODO: We should not multiply with 10 here.
> > x_a.set_ticks(np.arange(0, 2*np.pi*10+1, np.pi*10/4))
> > y_a.set_ticks(np.arange(0, 1*np.pi*10+1, np.pi*10/4))
> > labels = [
> >     r'$0$',
> >     r'$\frac{1}{4}\pi$',
> >     r'$\frac{1}{2}\pi$',
> >     r'$\frac{3}{4}\pi$',
> >     r'$\pi$',
> >     r'$\frac{5}{4}\pi$',
> >     r'$\frac{3}{2}\pi$',
> >     r'$\frac{7}{4}\pi$',
> >     r'$2 \pi$']
> > a.set_xticklabels(labels)
> > a.set_yticklabels(labels[:5])
> >
> > # show
> > plt.show()
>
> (The plot looks like a double swirl, if anyone is interested in that
> information)
>
> At first I do not know why I have to multiply with 10 at the ticks, but
> thats not the point.
>
> It is much more important that I would like to set the image to a
> certain width before saving. It should be both "tight" and "equal", so
> after setting the width the height could be calculated automatically.
>
> As a workaround I use the images and strech them vertically, but then
> the x/y axis tick labels look strange.
>
> So: How to set a certain width?
>
> Thanks and a merry Christmas,
> Keba

You can try

>>> ax.set_aspect('equal')
>>> ax.autoscale(tight=True)

The order doesn't seem to matter.

-Tony