Hello,
When trying to use kwant with matplotlib 1.4.0 (which is the last
released version), I had a problem when trying to draw a system. For
exemple, the following code
import kwant
import matplotlib as mpl
import matplotlib.pyplot as plt
%matplotlib inline # to be used in ipython notebook
lat = kwant.lattice.square(1.)
sys = kwant.Builder()
sys[(lat(x, y) for x in xrange(20) for y in xrange(10))] = 1.
sys[lat.neighbors(1)] = 1.
lead = kwant.Builder(kwant.TranslationalSymmetry((-1, 0)))
lead[(lat(0, y) for y in xrange(10))] = 1.
sys.attach_lead(lead)
sys.attach_lead(lead.reversed())
p = kwant.plot(sys, show=False)
plt.show()
produces a huge traceback ending with
ValueError: Transforms must be a Nx3x3 numpy array
The exact result depends on the matplotlib backend, but when an image is
produced, the sites of the leads are not drawn.
The bug seems to come from an update in matplotlib API, and is (in this
case) fixed by changing line 94 of plotter.py
(http://git.kwant-project.org/kwant/tree/kwant/plotter.py#n94) from
self._transforms = [matplotlib.transforms.Affine2D().scale(x) for x in
sizes]
to
self._transforms =
[matplotlib.transforms.Affine2D().scale(x).get_matrix() for x in sizes]
There may be other instances of this in kwant, but fixing this one is
enough to make the previous code work. A similar issue in 3D is
described in
https://www.mail-archive.com/[email protected]/msg00111.html
(I did not look further into this one.)
Best,
Michel
