# Python List: Why do we create two types of empty lists some times?

Hi all,

I have been struggling to understand the differences in creating a new list that some times is empty [ ] or some times it as a zero in it [0]?

test_list = [ ]

vs

test_list = [0]

Can someone please explain the rationale behind setting it to 0 or nothing?

my understanding so far is that if it is empty [ ], that means we do not want to specify any type of input for the list, and when we put a [0], then we treat it as index for later referencing or we want the list to begin at index 0?

Hi @sharknaut,

How we initialize a `list` depends on its purpose.

If we create a `list` for accumulating items that meet specified criteria, we usually initialize it as an empty `list`, then add items that meet those criteria. Following is an example:

``````numbers = [2, 3, 5, 7, 9, 6, 8]
# list for numbers divisible by three
divisible_by_three = []
for number in numbers:
if number % 3 == 0:
divisible_by_three.append(number)
print(divisible_by_three)
``````

Output:

``````[3, 9, 6]
``````

So that we can discuss a `list` that we initialize with a `0` in it, please post an example of pertinent code, or provide us with a link to an exercise that offers such an example.

Thank you appylpye,

great explanation for empty list.

the [ 0 ] example one of it is in this example:
Max Num Challenge

code:

``````#Write your function here
def max_num(nums):
maximum = nums[0]
for number in nums:
if number > maximum:
maximum = number
return maximum

#Uncomment the line below when your function is done
print(max_num([50, -10, 0, 75, 20]))
``````

``````test_list = [ ]

# vs

test_list = [0]
``````

should have been:

``````test_list = [ ]

# vs

test_list[0]
``````

those things are very different, `test_list = []` will create a new list, while `test_list[0]` will access the first element (at index 0) of an `test_list`

once a list has been defined, we can access elements in the list by index (position)

You are right, I did notice this myself just now.

Thank you for pointing it out, it makes more sense now in these exercises.

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