How to get specific elements from list in python
Last Updated :
16 Nov, 2024
In this article, we will learn how to get specific item(s) from given list. There are multiple methods to achieve this. Most simple method is accessing list item by Index.
Python
a = [1, 'geeks', 3, 'for', 5]
# accessing specific list item with their indices
item1 = a[1]
item3 = a[2]
item5 = a[4]
# negative indexing to get last element, same as a[4]
item_5 = a[-1]
print(item1, item3, item5, item_5)
To get multiple items at once through index, you can create a list of indices and iterate to access those items.
Python
a = [1, 'geeks', 3, 'for', 5]
# list of indices
index = [1, 2, 4]
for i in index:
print(a[i])
# comprehensive way of writing above for loop
# print([a[i] for i in index])
Using List Slicing [ to access range of elements]
By using slicing, you can access range of elements by specifying start and end index.
Python
a = [1, 'geeks', 3, 'for', 5]
# Accessing elements from index 1 to 3 (excluding 4)
a1 = a[1:4] # ['geeks', 3, 'for']
# Accessing elements from start to index 3 (excluding 4)
a2 = a[:4] # [1, 'geeks', 3, 'for']
# Accessing elements from index 2 to the end
a3 = a[2:] # [3, 'for', 5]
# Accessing every second element
a4 = a[::2] # [1, 3, 5]
print(a1, a2, a3, a4)
Output['geeks', 3, 'for'] [1, 'geeks', 3, 'for'] [3, 'for', 5] [1, 3, 5]
Using Slicing is unsuitable if the indices you want are not contiguous or don't follow regular pattern.
Using itemgetter() Function [Pythonic and Efficient Approach]
operator.itemgetter function gives better performance as compared to For Loop or comprehension. It can take multiple indices at once and return a tuple.
Python
from operator import itemgetter
a = [1, 'geeks', 3, 'for', 5]
a1 = itemgetter(1, 3)(a)
print(a1)
Get specific elements from a List (based on condition)
To get the elements based on some condition, you can use List comprehension and filter() method. Let's understand them with help of examples.
Using List Comprehension -
Python
a = [10, 20, 30, 40, 50]
# Extract elements greater than 20
a1 = [i for i in a if i > 20]
print(a1)
Using filter() method -
Let's do the same operation as above, using filter() method with lambda function.
Python
a = [10, 20, 30, 40, 50]
# Filter with a lambda function
a1 = list(filter(lambda x: x > 20, a)) # [30, 40, 50]
print(a1)
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