memory management - How to create a list or tuple of empty lists in Python? -

i need incrementally fill list or tuple of lists. looks this:

result = [] firsttime = true in range(x):     j in somelistofelements:         if firsttime:             result.append([f(j)])         else:             result[i].append(j) 

in order make less verbose more elegant, thought preallocate list of empty lists

result = createlistofemptylists(x) in range(x):     j in somelistofelements:         result[i].append(j) 

the preallocation part isn't obvious me. when result = [[]] * x, receive list of x references same list, output of following

result[0].append(10) print result 

is:

[[10], [10], [10], [10], [10], [10], [10], [10], [10], [10]] 

i can use loop (result = [[] in range(x)]), wonder whether "loopless" solution exists.

is way i'm looking

result = [list(somelistofelements) _ in xrange(x)] 

this make x distinct lists, each copy of somelistofelements list (each item in list reference, list in copy).

if makes more sense, consider using copy.deepcopy(somelistofelements)

generators , list comprehensions , things considered quite pythonic.