T = [L[i] for i in Idx]
Railsware
railsware.com › home › engineering › indexing and slicing for lists, tuples, strings, other sequential types in python
Python Indexing and Slicing for Lists, Tuples, Strings, other Sequential Types | Railsware Blog
January 22, 2025 - As it was shown, indexing allows you to access/change/delete only a single cell of a list. What if we want to get a sublist of the list. Or we want to update a bunch of cells at once? Or we want to go on a frenzy and extend a list with an arbitrary number of new cells in any position? Those and lots of other cool tricks can be done with slice notation. Let’s look at this subject – feel free to follow along on your own editor or with an online Python compiler.
W3Schools
w3schools.com › Python › ref_list_index.asp
Python List index() Method
Remove List Duplicates Reverse ... Interview Q&A Python Bootcamp Python Training ... The index() method returns the position at the first occurrence of the specified value....
In Python, how do I index a list with another list? - Stack Overflow
A quick timing test (no pysco or ... the list comprehension 2.5x faster than the loop (1000 elements, repeated 10000 times). 2009-06-18T12:00:29.357Z+00:00 ... (using map and a lambda is even slower - to be expected, since it calls a function for each iteration) 2009-06-18T12:03:31.893Z+00:00 ... +1 If the indexing list is arbitrary, ... More on stackoverflow.com
New to python, how can I get index of item in list?
I tried collection.index(33) I then get the error "must be str, not int" That would mean that collection isn't a list but something else. When I try with a list it works as expected: >>> collection = [1,2,3,4,5,6,7,8] >>> collection.index(1) 0 >>> collection.index(33) Traceback (most recent call last): File "", line 1, in ValueError: 33 is not in list Of course it would help if you supplied your code, preferrably uploaded to a text site like pastebin.com or gist.github.com. More on reddit.com
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December 13, 2017Regarding list slicing: can anyone help me understand the reasoning behind inclusive vs. exclusive indexing with negative vs. non-negative integers?
[-1] refers to the last element, so list[0:-1] gives you all but the last element in the same exclusive manner as you saw with positive indices. More on reddit.com
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April 27, 2019list index out of range
The length is returning 3, the index is 0 - 2. Sometimes you randomly get 3 and the error message.
More on reddit.com 8
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October 26, 2018Videos
07:28
Indexing and Slicing Python Lists for Beginners - YouTube
13:51
Python Lists for Beginners - List Indexing, List Methods, List ...
16:51
How to Access Lists in Python (Indexing & Slicing Explained) | ...
05:31
How To Iterate Through A List With Index In Python - YouTube
03:34
How To Find Index Of Item In List Python - YouTube
Accessing Items in a List using Indexing in Python - YouTube
Reddit
reddit.com › r/learnpython › embarrassingly, i don't understand how list indexing works
r/learnpython on Reddit: Embarrassingly, i don't understand how list indexing works
August 31, 2024 -
I'm learning data structure and algorithms and i came across a question in the list section. i thought after i had understood python, i had understood list but a question was asked and i find myself finding it hard to understand how the list indexing works.
here's the sample code:
arr = [1, 2, 3, 4, 5, 6]
for i in range(1, 6):
arr[i - 1] = arr[i]
for i in range(0, 6):
print(arr[i], end = " ")
it looks simple to understand but, i just can't understand it.
Top answer 1 of 5
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Let us step back a little. Before understanding your example, try to grok the example below for i in range(0, 3): print(i) which results in: 0 1 2 And the example below my_list = [42, 6, 2024] for i in range(0, 3): print(i, my_list[i]) Which results in: 0 42 1 6 2 2024 Are those clear to ya? Thanks!
2 of 5
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What don't you understand?
Python documentation
docs.python.org › 3 › tutorial › datastructures.html
5. Data Structures — Python 3.14.6 documentation
Remove all items from the list. Similar to del a[:]. ... Return zero-based index of the first occurrence of value in the list.
Top answer 1 of 8
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T = [L[i] for i in Idx]
2 of 8
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If you are using numpy, you can perform extended slicing like that:
>>> import numpy
>>> a=numpy.array(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'])
>>> Idx = [0, 3, 7]
>>> a[Idx]
array(['a', 'd', 'h'],
dtype='|S1')
...and is probably much faster (if performance is enough of a concern to to bother with the numpy import)
GeeksforGeeks
geeksforgeeks.org › python › python-list-index
Python List index() - Find Index of Item - GeeksforGeeks
DSA Python · Data Science · NumPy · Pandas · Practice · Django · Flask · Last Updated : 17 Jul, 2026 · index() method is used to find the position of an element in a list.
Published 6 hours ago
HackerEarth
hackerearth.com › practice › notes › samarthbhargav › a-quick-intro-to-indexing-in-python
A Quick intro to Indexing in Python - Samarth Bhargav
python lists are 0-indexed. So the first element is 0, second is 1, so on. So if the there are n elements in a list, the last element is n-1.
Codefinity
codefinity.com › courses › v2 › 102a5c09-d0fd-4d74-b116-a7f25cb8d9fe › 39cc7383-2374-4f3f-b322-2cb0109e6427 › df1b5ff1-bf08-4631-a38b-71e45b0101c0
Learn List Indexing in Python | Mastering Python Lists
In Python, lists allow you to access individual elements using their index. Indexing starts at 0, meaning the first element in a list is at index 0, the second element is at index 1, and so on. This is called zero indexing.
GeeksforGeeks
geeksforgeeks.org › python › indexing-lists-of-lists-in-python
Indexing Lists Of Lists In Python - GeeksforGeeks
July 23, 2025 - Lists of lists, also known as nested lists or sometimes 2D lists, are powerful structures in Python for managing multi-dimensional data such as matrices or tables. Direct Indexing is the easiest way to access an element in a list of lists.
Google
developers.google.com › google for education › python › python lists
Python Lists | Python Education | Google for Developers
Python's built-in list type is defined using square brackets [ ] and elements are accessed using zero-based indexing.
freeCodeCamp
freecodecamp.org › news › slicing-and-indexing-in-python
Slicing and Indexing in Python – Explained with Examples
December 11, 2025 - In Python, indexing starts from 0, which means the first element in a sequence is at position 0, the second element is at position 1, and so on. To access an element in a sequence, you can use square brackets [] with the index of the element ...
Medium
medium.com › @tuenguyends › pythons-list-type-part-1-indexing-and-slicing-23ad68ca4c66
Python’s list type (part 1) — Indexing and slicing | by Tue Nguyen | Medium
April 15, 2022 - Each element can be access using its position (or index) in the sequence. Python starts indexing at 0, thus if a sequence has N elements, then the elements are indexed by 0, 1, ..., N-1.
Programiz
programiz.com › python-programming › methods › list › index
Python List index()
The index() method returns the index of the given element in the list.
Logicalpython
logicalpython.com › python-list-indexing-slicing
Python List – Indexing and Slicing – Logical Python
As a Python list is an ordered sequence, each item is assigned the index position starting with 0.
Kochiva
kochiva.com › home › python list index( ) method – explained with practical examples
Python List Index() Method - Explained with Practical Examples
September 26, 2024 - This way you will have the index position of the 2nd occurrence of Alice in the list. ... The index function in Python follows the same index across all data structures.
Real Python
realpython.com › lessons › indexing-and-slicing
Indexing and Slicing (Video) – Real Python
00:47 Here’s a. As described, indexes are zero-based for lists, so a[0] would access the first item in that list. 01:03 a[2] would access the third one. And in this case, a[5] would access the last. Another way to get there would be a and the len() (length) of a minus 1. 01:18 If you use an index value that’s too high, Python will raise an exception—an IndexError saying that the list index is out of range.
Published September 3, 2019
Learnlearn
revise.learnlearn.uk › app › section › 2053 › 613
List Indexing Basics
Accessing list elements is a fundamental concept in programming that involves retrieving values stored in a list using their index. In programming languages like Python, lists are indexed starting from 0, meaning the first element has an index of 0.
Codecademy
codecademy.com › docs › python › lists › .index()
Python | Lists | .index() | Codecademy
June 11, 2025 - Unlike the in operator which only returns a boolean value, .index() provides the exact numerical position needed for precise list operations. ... Looking for an introduction to the theory behind programming? Master Python while learning data structures, algorithms, and more!
Purple Frog Systems
purplefrogsystems.com › home › python lists – what do i need to know?
Python Lists – What do I need to know? - Purple Frog Systems
July 22, 2025 - Access elements of a list using list[index]. Indexing in Python starts at 0, which means that the first element has an index of 0.
Tutorialspoint
tutorialspoint.com › python › list_index.htm
Python List index() Method
The Python List index() method is used to retrieve the lowest index in a list at which a specified object appears. The object can be anything; a single element or a collection of elements in the form of another list, tuple, set etc.