Caveats Linear time-complexity in list length An index call checks every element of the list in order, until it finds a match. If the list is long, and if there is no guarantee that the value will be near the …

14 I wasn't happy with any of these approaches, so I came up with a Flexlist class that allows for flexible indexing, either by integer, slice or index-list:

18 List indexes of -x mean the xth item from the end of the list, so n[-1] means the last item in the list n. Any good Python tutorial should have told you this.

Dec 13, 2008 · I am iterating over a list and I want to print out the index of the item if it meets a certain condition. How would I do this? Example: testlist = [1,2,3,5,3,1,2,1,6] for item in testlist: if

index() will give the first occurrence of an item in a list. Is there a neat trick which returns all indices in a list for an element?

Here's the timeit comparison of all the answers with list of 1000 elements on Python 3.9.1 and Python 2.7.16. Answers are listed in the order of performance for both the Python versions.

86 In Python, you wouldn't use indexes for this at all, but just deal with the values— [value for value in a if value > 2]. Usually dealing with indexes means you're not doing something the best way.

Aug 11, 2022 · The way Python indexing works is that it starts at 0, so the first number of your list would be [0]. You would have to print [52], as the starting index is 0 and therefore line 53 is [52].

The range here enumerates elements of your list and since we want only those where self.states is True, we are applying a filter based on this condition. For Python > 3.0:

Aug 19, 2015 · Closed 6 years ago. If you have a list in python, and want to extract elements at indices 1, 2 and 5 into a new list, how would you do this? This is how I did it, but I'm not very satisfied: