>>> a = [1,1,2,3,1,2,-2,-4,1,56,12,-23,-3,12,323,23]
>>> print len(a)
16
>>> print len([i for i in a if i%2])
9
>>> print sum([i for i in a if i == 1])
4

>>> import functools
... import operator
... 
... def product(seq):
...     """Product of a sequence."""
...     return functools.reduce(operator.mul, seq, 1)
>>> product([i for i in a if i>0])
48: 718889472
>>> sorted_list = sorted(a[:len(a)/2]) + (sorted(a[len(a)/2:], reverse=True))
>>> print sorted_list
[-4, -2, 1, 1, 1, 2, 2, 3, 323, 56, 23, 12, 12, 1, -3, -23]