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from rdflib import Literal, XSD
from rdflib.plugins.sparql.evalutils import _eval, NotBoundError
from rdflib.plugins.sparql.operators import numeric
from rdflib.plugins.sparql.datatypes import type_promotion
from rdflib.plugins.sparql.compat import num_max, num_min
from decimal import Decimal
"""
Aggregation functions
"""
def _eval_rows(expr, group):
for row in group:
try:
yield _eval(expr, row)
except:
pass
def agg_Sum(a, group, bindings):
c = 0
dt = None
for x in group:
try:
e = _eval(a.vars, x)
n = numeric(e)
if dt == None:
dt = e.datatype
else:
dt = type_promotion(dt, e.datatype)
if type(c) == float and type(n) == Decimal:
c += float(n)
elif type(n) == float and type(c) == Decimal:
c = float(c) + n
else:
c += n
except:
pass # simply dont count
bindings[a.res] = Literal(c, datatype=dt)
# Perhaps TODO: keep datatype for max/min?
def agg_Min(a, group, bindings):
m = None
for x in group:
try:
v = numeric(_eval(a.vars, x))
if m is None:
m = v
else:
m = num_min(v, m)
except:
return # error in aggregate => no binding
if m is not None:
bindings[a.res] = Literal(m)
def agg_Max(a, group, bindings):
m = None
for x in group:
try:
v = numeric(_eval(a.vars, x))
if m is None:
m = v
else:
m = num_max(v, m)
except:
return # error in aggregate => no binding
if m is not None:
bindings[a.res] = Literal(m)
def agg_Count(a, group, bindings):
c = 0
for x in group:
try:
if a.vars != '*':
try:
_eval(a.vars, x)
except NotBoundError:
continue
c += 1
except:
return # error in aggregate => no binding
# pass # simply dont count
bindings[a.res] = Literal(c)
def agg_Sample(a, group, bindings):
for ctx in group:
try:
bindings[a.res] = _eval(a.vars, ctx)
break
except NotBoundError:
pass
def agg_GroupConcat(a, group, bindings):
sep = a.separator or " "
bindings[a.res] = Literal(
sep.join(unicode(x) for x in _eval_rows(a.vars, group)))
def agg_Avg(a, group, bindings):
c = 0
s = 0
dt = None
for x in group:
try:
e = _eval(a.vars, x)
n = numeric(e)
if dt == None:
dt = e.datatype
else:
dt = type_promotion(dt, e.datatype)
if type(s) == float and type(n) == Decimal:
s += float(n)
elif type(n) == float and type(s) == Decimal:
s = float(s) + n
else:
s += n
c += 1
except:
return # error in aggregate => no binding
if c == 0:
bindings[a.res] = Literal(0)
if dt == XSD.float or dt == XSD.double:
bindings[a.res] = Literal(s / c)
else:
bindings[a.res] = Literal(Decimal(s) / Decimal(c))
def evalAgg(a, group, bindings):
if a.name == 'Aggregate_Count':
return agg_Count(a, group, bindings)
elif a.name == 'Aggregate_Sum':
return agg_Sum(a, group, bindings)
elif a.name == 'Aggregate_Sample':
return agg_Sample(a, group, bindings)
elif a.name == 'Aggregate_GroupConcat':
return agg_GroupConcat(a, group, bindings)
elif a.name == 'Aggregate_Avg':
return agg_Avg(a, group, bindings)
elif a.name == 'Aggregate_Min':
return agg_Min(a, group, bindings)
elif a.name == 'Aggregate_Max':
return agg_Max(a, group, bindings)
else:
raise Exception("Unknown aggregate function " + a.name)
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