[Kwant] putting disorder (kwant.digest.uniform) in graphene with shape function

[Sudin Ganguly]

Dear Sir,

I'm trying to put disorder in graphene with shape function. I got some
help from the link:

http://nullege.com/codes/show/src@k@w@kwant-1.0.0@kwant@tests@test_comprehensive.py/12/kwant.digest.gauss

But when I want to see the onsite values using the comment below,

kwant.plotter.plot(sys_2['sys'],site_color=lambda site:
sys_2['sys'][site],colorbar = True, cmap='gist_heat')

It says, "cannot convert argument to rgb sequence".

Is there any way to see the onsite values through plot?

Also it seems that all the onsite values have the same disorder. Can I
make them different using kwant.digest.uniform()?

Here is my code.

#====================================
import kwant
from matplotlib import pyplot

def onsite(site, salt):
        return  kwant.digest.uniform(repr(site), salt) - 0.5

def make_sys(l, w):
        def rect(pos):
                x, y = pos
                return 0 < x < l and 0 < y < w

        sys=kwant.Builder()
        lat = kwant.lattice.honeycomb()
        a,b= lat.sublattices

        sys[lat.shape(rect, (1, 1))] = onsite
        sys[lat.neighbors()] = -1

    # left lead
        sym = kwant.TranslationalSymmetry((-1,0))
        sym.add_site_family(lat.sublattices[0], other_vectors=[(-1, 2)])
        sym.add_site_family(lat.sublattices[1], other_vectors=[(-1, 2)])

        def lead_shape(pos):
                x, y = pos
                return 0 < y < w

        lead = kwant.Builder(sym)
        lead[lat.shape(lead_shape, (1, 1))] = 0
        lead[lat.neighbors()] = -1
        sys.attach_lead(lead)
        sys.attach_lead(lead.reversed())

        return {'sys': sys }

def main():
        sys_2 = make_sys(l=10, w=23)
        kwant.plotter.plot(sys_2['sys'],site_color=lambda site:
sys_2['sys'][site],colorbar = True, cmap='gist_heat')

# Call the main function if the script gets executed (as opposed to
imported).
# See <http://docs.python.org/library/__main__.html>.
if __name__ == '__main__':
        main()
#============================================




With Regards,
Sudin