def get_credibility(comparables_a, comparables_b, concordance, discordance,
with_denominator, only_max_discordance, cv_crossed):
def _get_credibility_idx(x, y, num_crossed, only_max_discordance):
discordance_values = discordance[x][y].values()
if set(discordance_values) == set([0]): # only zeros
c_idx = concordance[x][y]
elif 1 in discordance_values: # at least one '1'
if not concordance[x][y] < 1:
raise RuntimeError("When discordance == 1, "
"concordance must be < 1.")
c_idx = 0.0
elif only_max_discordance and not with_denominator:
c_idx = concordance[x][y] * (1 - max(discordance_values))
else:
factors = []
for d in discordance_values:
if with_denominator:
if d > concordance[x][y]:
factor = (1 - d) / (1 - concordance[x][y])
else:
factor = None
else:
factor = (1 - d)
if factor:
factors.append(factor)
if factors == []:
c_idx = concordance[x][y]
else:
discordance_aggr = reduce(lambda f1, f2: f1 * f2, factors)
c_idx = (concordance[x][y] *
discordance_aggr**(1 - num_crossed / num_total))
return c_idx
two_way_comparison = True if comparables_a != comparables_b else False
# 'num_total' == total number of criteria.
# Instead of this monstrosity below, maybe it would be better to provide
# 'criteria.xml' as another input..?
num_total = len(discordance.values()[0].values()[0].keys())
credibility = Vividict()
for a in comparables_a:
for b in comparables_b:
num_crossed = len(cv_crossed[a][b])
credibility[a][b] = _get_credibility_idx(a, b, num_crossed,
only_max_discordance)
if two_way_comparison:
credibility[b][a] = _get_credibility_idx(
b, a, num_crossed, only_max_discordance)
return credibility