CODEWITHSUNDEEP
pythonlist
M. Paul
M. Paul

Reputation: 391

how can I assign the list with zeroes when number of elements is unknown to me

I want to store the number of copies of different books in a list as [10,14,12,16,42,23]. Here the first element i.e.of index[0] represents first book has 10 copies, second book (index[1]) has 14 copies like this. But the problem is that I don't know how many kind of books exists, i.e. total number of elements of list is unknown. so that i created an empty list as below:

li = []

After that I run a for loop and in each iteration I want to add and update the list element as follows:

for x in range(5):
    li[x] = li[x] + 1

But I am getting the following error: li[x] = li[x] + 1 IndexError: list index out of range Because li[x] has not been assigned to 0 or any value. My question is how can I assign the list with zeroes when number of elements is unknown to me and I am appending the list elements dynamically. Please suggest some approach to achieve my requirement.

Upvotes: 0

Views: 101

Answers (2)

Abhinav Anand
Abhinav Anand

Reputation: 639

Try this :

> li = [0] * 5

This is how li will look like :

> li =  [0, 0, 0, 0]

Since you don't know the size so all you can do is to create a list

> li = []

and after some condition keep appending zero to it

> if condition: 
     li.append(0)

Upvotes: 0

Harsha Biyani
Harsha Biyani

Reputation: 7268

You can assign 0 as a value in the list. You can try :

>>> for x in range(5):
      li.append(0)

>>> print li
[0, 0, 0, 0, 0]

>>> for x in range(5):
      li[x] = li[x] + 1 

>>> print li
[1, 1, 1, 1, 1]

Upvotes: 1

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