On Fri, Nov 20, 2015 at 6:39 PM, Chris Angelico <ros...@gmail.com> wrote:
> My crystal ball suggests that defaultdict(list) might be useful here.
>
> ChrisA
I used something similar to this for some problem in hackerrank,
anyway i think this is what you want.
class defaultlist(object):
def __init__(self, factory, data=None):
self.factory = factory
self.list = []
self.data = data
def __getitem__(self, x):
if x >= len(self.list):
self.list.extend([self.factory() for _ in
range(len(self.list), x + 1)])
return self.list[x]
def __repr__(self):
return str(self)
def __str__(self):
if len(self.list) == 0:
return '(' + str(self.data) + ')[...]'
return ''.join(['(', str(self.data), ')['] + map(str,
self.list) + [', ...]'])
def __setitem__(self, x, v):
if x >= len(self.list):
self.list.extend([self.factory() for _ in
range(len(self.list), x + 1)])
self.list[x] = v
def main():
factory = lambda: defaultlist(factory)
list_of_lists = defaultlist(factory)
print (list_of_lists[0])
list_of_lists[0][10].data = 20
print (list_of_lists[0])
main()
Gist: https://gist.github.com/c0c2ee1e7c6535ef8c3d
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