On 28 June 2013 15:38, Vincent Davis <vinc...@vincentdavis.net> wrote:
> I have a list of a list of integers. The lists are long so i cant really
> show an actual example of on of the lists, but I know that they contain only
> the integers 1,2,3,4. so for example.
> s2 = [[1,2,2,3,2,1,4,4],[2,4,3,2,3,1]]
>
> I am calculating the product, sum, max, min.... of each list in s2 but I get
> negative or 0 for the product for a lot of the lists. (I am doing this in
> ipython)
>
> for x in s2:
> print('len = ', len(x), 'sum = ', sum(x), 'prod = ', prod(x), 'max = ',
> max(x), 'min = ', min(x))
>
> ...
>
> ('len = ', 100, 'sum = ', 247, 'prod = ', 0, 'max = ', 4, 'min = ', 1)
> ('len = ', 100, 'sum = ', 230, 'prod = ', -4611686018427387904, 'max = ', 4,
> 'min = ', 1)
> ('len = ', 100, 'sum = ', 261, 'prod = ', 0, 'max = ', 4, 'min = ', 1)
>
> .....
>
> ('prod =', 0, 'max =', 4, 'min =', 1)
> ('prod =', 1729382256910270464, 'max =', 4, 'min =', 1)
> ('prod =', 0, 'max =', 4, 'min =', 1)
>
> ....
>
>
> Whats going on?
Let me guess.
These are your lists (sorted):
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4]
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4]
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
4, 4, 4, 4, 4, 4, 4, 4]
You are using numpy.prod()
Numpy.prod overflows:
>>> numpy.prod([-9223372036854775808, 2])
... 0
You want to use something that doesn't such as:
def prod(iter):
p = 1
for elem in iter:
p *= elem
return p
and then you get your correct products:
8002414661101704746694488837062656
3907429033741066770846918377472
682872717747345471717929714096013312
--
http://mail.python.org/mailman/listinfo/python-list
