from operator import itemgetter
l=[1,2,3,4,5,6,7,8,9,10,1,2,3,4,12,1,45,1,2,1]
for value in l:
    enum_l=enumerate(l)
    print  value, "===>",
    res = filter(lambda (index, val): val==value, enum_l)
    print map(itemgetter(0), res)
        

from collections import deque
l=deque([1,2,3,4,5,6,7,8,9,10,1,2,3,4,12,1,45,1,2,1])
tested = set()
count = 0
while l:
    value = l.popleft()
    count += 1
    if value in tested:
        continue
    tested.add(value)
    res = [x[0] for x in enumerate(l, count) if x[1] == value]
    if res:
        print(value, "===>", res)

from operator import itemgetter
l=[1,2,3,4,5,6,7,8,9,10,1,2,3,4,12,1,45,1,2,1]
for value in set( x for x in l if l.count(x)>1 ):
    enum_l=enumerate(l)
    res = filter(lambda (index, val): val==value, enum_l)[1:]
    print value, "===>", map(itemgetter(0), res)

from operator import itemgetter
res=filter (lambda (a,b): len(b)>0, [ (x, map(lambda i:i[0], list(y)[1:]) ) for x, y in groupby(sorted(enumerate(l), key=itemgetter(1)), key=itemgetter(1))] )
print a    

from collections import defaultdict
l=[1,2,3,4,5,6,7,8,9,10,1,2,3,4,12,1,45,1,2,1]
res = defaultdict(list)
for pos, item in enumerate(l):
    res[item].append(pos)
print [(k,v[1:]) for k,v in res.items() if len(v)>1]