from graphs.graphIO import loadgraph, writeDOT
from tristan.isomorphisms import bijection, colordict
from tristan.refinement import hopcroft
"""
Test if bijection works.
"""
l = loadgraph('../../test_grafen/colorref_smallexample_2_49.grl', readlist=True)
hopcroft(l[0][1])
hopcroft(l[0][2])
print(bijection(colordict(l[0][1]),colordict(l[0][2])))
def isomorphisms(g1t, g2t, count=False):
"""
Counts or determines the isomorphisms between two graphs.
:param g1t: The first graph
:param g2t: The second graph
:param count: Count the amount of isomorphisms or determine only if there are isomorphisms.
:return:
"""
# Generate copies of the graphs to avoid pointer collision
g1 = copygraph(g1t)
g2 = copygraph(g2t)
# Union graphs g1 and g2
union = graph()
union.createUnion(g1, g2)
# Compute coarsest stable coloring that refines (g1, g2)
hopcroft(union)
# Generate color dictionaries
g1colors = colordict(g1.V())
g2colors = colordict(g2.V())
ucolors = colordict(union)
# Check if the graphs are balanced
if not balanced(g1colors, g2colors):
return 0
# Check if the graphs define a bijection
if bijection(g1colors, g2colors):
return 1
# Choose a color class with |C| >= 4. The first element fulfills.
for cc in g1colors:
if len(g1colors[cc]) > 1 and len(g2colors[cc]) > 1:
colorclass = cc
break
x = g1colors[colorclass][0]
# Determine the maxvalue in the color dictionary
for i in range(len(g1colors)+1):
if i not in g1colors:
maxvalue = i
break
# Set the new colorclass of x.
xoldcolornum = x.getcolornum()
x.setcolornum(maxvalue)
g1colors = colordict(copygraph(g1).V())
# Count number of automorphisms
num = 0
# Loop all y in C & g2.V()
for y in g2colors[colorclass]:
# Set the new colorclass of y, preserve the old color class
yoldcolornum = y.getcolornum()
y.setcolornum(maxvalue)
g2colors = colordict(g2.V())
if count:
# Count all automorphisms
num = num + isomorphisms(g1, g2, count)
else:
# Only one automorphism fulfills
return isomorphisms(g1, g2)
# Reset the colornum of y
y.setcolornum(yoldcolornum)
# Reset the colornum of x
x.setcolornum(xoldcolornum)
# Return the number of automorphisms
return num
