fix advanced_construction to use tinyarray and new symmetry

examples/advanced_construction.py

@@ -2,25 +2,25 @@
 
 from __future__ import division
 import kwant
-import numpy
-from math import tanh, sqrt
+import tinyarray as ta
+from math import tanh
 
 
 def make_system(R=50):
-    sigma_0 = numpy.identity(2)
-    sigma_x = numpy.array([[0, 1], [1, 0]])
-    sigma_y = numpy.array([[0, -1j], [1j, 0]])
-    sigma_z = numpy.array([[1, 0], [0, -1]])
+    sigma_0 = ta.identity(2)
+    sigma_x = ta.array([[0, 1], [1, 0]])
+    sigma_y = ta.array([[0, -1j], [1j, 0]])
+    sigma_z = ta.array([[1, 0], [0, -1]])
 
     def in_ring(pos):
-        return R**2 / 4 < pos[0]**2 + pos[1]**2 < R**2
+        return R ** 2 / 4 < pos[0] ** 2 + pos[1] ** 2 < R ** 2
 
     def pot(site):
         x, y = site.pos
         return (0.1 * tanh(x / R) + tanh(2 * y / R)) * sigma_z
 
     def in_lead(pos):
-        return -1 < pos[0] < 1.3 and - R/4 < pos[1] < R/4
+        return -1 < pos[0] < 1.3 and -R / 4 < pos[1] < R / 4
 
     lat = kwant.lattice.Honeycomb()
 
@@ -29,8 +29,8 @@ def make_system(R=50):
     for hopping in lat.nearest:
         sys[sys.possible_hoppings(*hopping)] = sigma_y
 
-    lead = kwant.Builder(kwant.TranslationalSymmetry([lat.vec((-1, 0))]))
-    lead[lat.shape(in_lead, (0,0))] = sigma_0
+    lead = kwant.Builder(kwant.TranslationalSymmetry(lat.vec((-1, 0))))
+    lead[lat.shape(in_lead, (0, 0))] = sigma_0
     for hopping in lat.nearest:
         lead[lead.possible_hoppings(*hopping)] = sigma_x
     sys.attach_lead(lead)