Question

How can I make a function that will create a list, increasing the amount of numbers it contains each time to a specified value?

For example if the max was 4, the list would contain

1, 2, 2, 3, 3, 3, 4, 4, 4, 4

It’s difficult to explain what I’m looking for, but from the example I think you’ll understand!

Thanks

Answer 1

A Nested loop.
This would be a very basic way to do it.
There are much better ways, this should give you the general idea.

>>> def listmaker(num):
    l = []
    for i in xrange(1, num+1):
        for j in xrange(i):
            l.append(i)
    return l

>>> print listmaker(4)
[1, 2, 2, 3, 3, 3, 4, 4, 4, 4]

Here is doing it with list comprehension:

>>> def listmaker2(num):
    return [y for z in [[x]*(x) for x in xrange(1, num+1)] for y in z]

>>> print listmaker2(4)
[1, 2, 2, 3, 3, 3, 4, 4, 4, 4]

Using extend as suggested.

>>> def listmaker3(num):
    l = []
    for i in xrange(1, num+1):
        l.extend([i]*(i))
    return l

>>> print listmaker3(4)
[1, 2, 2, 3, 3, 3, 4, 4, 4, 4]