Как найти число, встречающееся чаще всего?

frequency = {}
for x in mylist:
    frequency[x] = frequency.get(x, 0)+1
max([(k,v) for k,v in frequency.iteritems()], key = lambda x:x[1])[0]

>>> def f(lst):
...     nums = {}
...     n, nm = None, 0
...     for i in lst:
...         nums[i] = t = nums.get(i, 0) + 1
...         if t > nm:
...             n, nm = i, t
...     return n
... 
>>> f([3, 5, 1, 2, 5])
5
>>>

mylist = [3, 5, 1, 1, 1, 1, 1, 1, 1, 1, 2, 5, 5, 5, 5, 5]
keys = set(mylist)
frequency = dict([(k, len(filter(lambda x: x == k, mylist))) for k in keys])
print frequency
mymax = max([(k,v) for k,v in frequency.iteritems()], key = lambda x:x[1])[0]
print mymax

>>> import timeit
>>> import collections
>>> 
>>> def f1(lst):
...     elems = {}
...     e, em = None, 0
...     for i in lst:
...         elems[i] = t = elems.get(i, 0) + 1
...         if t > em:
...             e, em = i, t
...     return e
... 
>>> def f2(lst):
...     frequency = {}
...     for x in lst:
...         frequency[x] = frequency.get(x, 0)+1
...     return max([(k,v) for k,v in frequency.items()], key = lambda x:x[1])[0]
... 
>>> def f3(lst):
...     return collections.Counter(lst).most_common(1)[0][0]
... 
>>> t1 = timeit.Timer('f1([3, 5, 1, 2, 5])', 'from __main__ import f1')
>>> t2 = timeit.Timer('f2([3, 5, 1, 2, 5])', 'from __main__ import f2')
>>> t3 = timeit.Timer('f3([3, 5, 1, 2, 5])', 'from __main__ import f3')
>>> t1.repeat(3)
[2.0534028900000294, 2.069512689000021, 2.0679963759999964]
>>> t2.repeat(3)
[5.193368679000059, 5.286952303000021, 5.156681644999935]
>>> t3.repeat(3)
[18.053162295999982, 18.012273875000005, 18.20183160700003]
>>>