Related Articles
Python | Truncate a list
• Last Updated : 04 Jan, 2019

Sometimes there is a requirement to restrict the list size to a particular number and remove all the elements from list which occur after a certain number as decided as list size. This is a useful utility for web development using Python. Let’s discuss certain ways in which this can be performed.

Method #1 : Using `pop()`
`pop `function can be repeated a number of times till size of the list reaches the threshold required as the size of the list. This uses a whole loop and hence is comparatively tedious.

 `# Python3 code to demonstrate ``# to truncate list using pop()`` ` `# initializing list  ``test_list ``=` `[``1``, ``4``, ``5``, ``6``, ``7``, ``3``, ``8``, ``9``, ``10``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# size desired``k ``=` `5`` ` `# using pop()``# to truncate list ``n ``=` `len``(test_list)``for` `i ``in` `range``(``0``, n ``-` `k ):``    ``test_list.pop()`` ` `# printing result``print` `(``"The truncated list is : "` `+`  `str``(test_list))`
Output:
```The original list is : [1, 4, 5, 6, 7, 3, 8, 9, 10]
The truncated list is : [1, 4, 5, 6, 7]
```

Method #2 : Using del + list slice
`del `operator can be used to delete all the elements that appear after the specific index, which is handled by the list slicing technique.

 `# Python3 code to demonstrate ``# to truncate list ``# using del + list slicing`` ` `# initializing list  ``test_list ``=` `[``1``, ``4``, ``5``, ``6``, ``7``, ``3``, ``8``, ``9``, ``10``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# size desired``k ``=` `5`` ` `# using del + list slicing``# to truncate list ``del` `test_list[``5``:]`` ` `# printing result``print` `(``"The truncated list is : "` `+`  `str``(test_list))`
Output:

```The original list is : [1, 4, 5, 6, 7, 3, 8, 9, 10]
The truncated list is : [1, 4, 5, 6, 7]
```

Method #3 : Using list slicing
In this method, we just slice the first K elements and ignore all the elements that occur after K elements. This is most pythonic and recommended method to perform this task.

 `# Python3 code to demonstrate ``# to truncate list ``# using list slicing`` ` `# initializing list  ``test_list ``=` `[``1``, ``4``, ``5``, ``6``, ``7``, ``3``, ``8``, ``9``, ``10``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# size desired``k ``=` `5`` ` `# using list slicing``# to truncate list ``res ``=` `test_list[``0` `: ``5``]`` ` `# printing result``print` `(``"The truncated list is : "` `+`  `str``(res))`
Output:
```The original list is : [1, 4, 5, 6, 7, 3, 8, 9, 10]
The truncated list is : [1, 4, 5, 6, 7]
```

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up