Q:

Find the index of an item given a list containing it in Python

belongs to collection: Python List Programs

mahmoud2506
Save to bookmark
|
2022-05-22
|
  299 
0

Syntax:

    list.index(x[, start[, end]])

The index() returns zero-based index in the list of the first item whose value is equal to x and raises a ValueError if there is no such item.

Arguments:

  • x = item whose lowest index will be returned
  • start and end (optional) = used to limit the search to a particular subsequence of the list
Python programming, examples, Python programming examples,
login and add your own answer to this question

All Answers

mahmoud2506
2022-05-22
need an explanation for this answer? contact us directly to get an explanation for this answer

Example Implementation

Scenario 1: retrieve index without providing optional arguments

-bash-4.2$ python3
Python 3.6.8 (default, Apr 25 2019, 21:02:35)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> test_list = ['bangalore','chennai','mangalore','vizag','delhi']
>>> print(test_list.index('bangalore'))
0
>>> test_list_1 = [1,2,3,4,5]
>>> print(test_list_1.index(4))
3

Scenario 2: retrieve index, providing the start and end limit

-bash-4.2$ python3
Python 3.6.8 (default, Apr 25 2019, 21:02:35)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> test_list = ['bangalore','chennai','mangalore','vizag','delhi']
#finds the item 'bangalore' only within 0th to 3rd element in list and returns the index
>>> print(test_list.index('bangalore',0,3))
0


#finds the item 'bangalore' only within 1st to 3rd element in list and returns the index, and since the item 'bangalore' is not in that range, we get the exception
>>> print(test_list.index('bangalore',1,3))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: 'bangalore' is not in list
>>>

Scenario 3: Demonstrating the ValueError

Python 3.6.8 (default, Apr 25 2019, 21:02:35)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> test_list = ['bangalore','chennai','mangalore','vizag','delhi']
>>> print(test_list.index('bhopal'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: 'bhopal' is not in list
>>>

need an explanation for this answer? contact us directly to get an explanation for this answer

total answers (1)

Python List Programs
This question belongs to these collections

Similar questions

need a help?

find thousands of online teachers now
Extract Even and odd number from a given list in P... >>
<< Python program for various list operations...