Populating a list/array by index in Python?

Question

Is this possible:

myList = []

myList[12] = \'a\'
myList[22] = \'b\'
myList[32] = \'c\'
myList[42] = \'d\'

When I try, I get:

#         


        

Answer 1

Here's a quick list wrapper that will auto-expand your list with zeros if you attempt to assign a value to a index past it's length.

class defaultlist(list):

   def __setitem__(self, index, value):
      size = len(self)
      if index >= size:
         self.extend(0 for _ in range(size, index + 1))

      list.__setitem__(self, index, value)

Now you can do this:

>>> a = defaultlist([1,2,3])
>>> a[1] = 5
[1,5,3]
>>> a[5] = 10
[1,5,3,0,0,10]