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Python Python Collections (2016, retired 2019) Lists Removing items from a list

Hendrik /
Hendrik /
13,961 Points
Posted by Hendrik /
Hendrik /
13,961 Points

Python Collections - Removing Items from a list Challenge Task 2

Hi!

I'm struggling with the 2nd task and can't seem to figure out the smartest way to remove the items from the list.

I tried 2 different approaches but and the Boolean Value is the only item I can't remove.

1st way:

messy_list = ["a", 2, 3, 1, False, [1, 2, 3]]

messy_list.insert(0, messy_list.pop(3))

for item in messy_list:

      if not isinstance(item, int):
            messy_list.remove(item)

2nd way:

messy_list = ["a", 2, 3, 1, False, [1, 2, 3]]

messy_list.insert(0, messy_list.pop(3))

for item in messy_list:

   try:
        item += 1

   except TypeError:
        messy_list.remove(item)

The code works with the strings and lists but it doesn't remove the Boolean Value. Can somebody of you explain me why?

Thank you!

4 Answers

Kenneth Love
STAFF
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

Don't be clever, just remove the value you want to remove. The smartest, and most Pythonic way, is to just do exactly what you want the first time.

That said, there is a way to do it with a loop but you'll need to use type() instead of isinstance()

Hendrik /
Hendrik /
13,961 Points
Hendrik /
Hendrik /
13,961 Points

Alright thank you! :)

Hendrik /
Hendrik /
13,961 Points
Hendrik /
Hendrik /
13,961 Points

Thank you! What do you think would be the best solution to that?

Saiteja Vemula
Saiteja Vemula
7,162 Points
Saiteja Vemula
Saiteja Vemula
7,162 Points

Sir, I've trouble with this code challenge. Here's my code

messy_list = ["a", 2, 3, 1, False, [1, 2, 3]]

# Your code goes below here
messy_list.insert(0,messy_list.pop(3))
i = 0
while i < len(messy_list) :
    if not type(i) == type(messy_list[i]):
        del messy_list[i]
    i += 1
Kenneth Love
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

You're changing the list as you go through it in a loop, which leads to skipped indexes. You'll need either a copy of the list or to just delete the items you want deleted instead of trying to solve this in a clever fashion.

Saiteja Vemula
Saiteja Vemula
7,162 Points
Saiteja Vemula
Saiteja Vemula
7,162 Points

Thank you sir for notifying me that indexes were skipped when I delete a value from the list while looping. I've solved the Task like this way and it worked.

messy_list = ["a", 2, 3, 1, False, [1, 2, 3]]
messy_list.insert(0,messy_list.pop(3))
count = 0
i = 0
while i < len(messy_list) :
    if not type(i) == type(messy_list[i]):
        del messy_list[i]
        messy_list.insert(i,'x')
        count += 1
    i += 1

while count:
    count -= 1
    messy_list.remove('x')
Jennifer Mitchell
Jennifer Mitchell
1,831 Points
Jennifer Mitchell
Jennifer Mitchell
1,831 Points

You don't need loops or tries to solve task 2. Just use del and the index of the items you want to remove from the list. Be aware the index changes as you remove items.