Remove elements larger than a specific value from a list in Python

In this article, we will learn to remove elements from a list that is larger than a specific value in Python.

Example 

Input: [12, 33, 10, 20, 25], value = 21

Output: [12, 10, 20]

Explanation: Removed all element from the list that are greater than 21.

Remove list elements greater than a given value using list comprehension

In the following example, we declare and assign a list of numbers to the variable num_list. With list comprehension, we can traverse each element from a list and perform an action on it. Here, we will check if the current number is less than or equal to 100. If true it will be returned as a list. We will assign the returned list to the same variable num_list.

Python3

num_list = [30, 200, 65, 88, 98, 500, 34]

# remove numbers using list comprehension
num_list = [i for i in num_list if i <= 100]

# display the list
print(num_list)

Output

[30, 65, 88, 98, 34]

Time Complexity: O(n)
Auxiliary Space: O(1)

Remove list elements greater than a given value using remove() method

In the following example, we will declare and assign a list num_list with numbers. We will remove numbers that are greater than 100 from the num_list. We will traverse each number from the list and check if the current number is greater than 100, if true we will remove it from the list using the Python remove() method. We will remove all values that are greater than the given number once we traverse the list.

Python3

num_list = [30, 200, 65, 88, 98, 500,102]

# traverse the numbers list
i=0
while i<len(num_list):

    # check if current number in the
    # list is greater than 100
    if num_list[i] > 100:

        # if true remove number from list
        num_list.remove(num_list[i])
    else:
      i+=1
      #increment of index value when item is not removed


# display the num_list after removing the
# values that are greater than 100
print(num_list)

Output

[30, 65, 88, 98]

Time Complexity: O(n) 
Auxiliary space: O(1)

Remove list elements greater than a given value using the filter() method and lambda function

Python3

num_list = [30, 200, 65, 88, 98, 500, 34]

num_list = list(filter(lambda x: x <= 100, num_list))

# display the num_list after removing the
# values that are greater than 100
print(num_list)

Output

[30, 65, 88, 98, 34]

Time complexity: O(n) 
Auxiliary Space: O(1)

Using Numpy:

Note: Install numpy module using command “pip install numpy”

Python3

# Remove list elements greater than a given value using numpy
import numpy as np

num_list = [30, 200, 65, 88, 98, 500, 34]

# convert list to numpy array
arr = np.array(num_list)

# remove numbers greater than 100
new_arr = arr[arr <= 100]

# display the new_arr after removing the
# values that are greater than 100
print(new_arr)

#This code is contributed by Edula Vinay Kumar Reddy

Output:

[30 65 88 98 34]

Time complexity: O(n) 
Auxiliary Space: O(1)

Using enum()

In this code, we use the enumerate() function to loop over the index and element of the num_list. Then, we filter the numbers using list comprehension just like before. The enumerate() function provides an elegant way to loop over the index and element of a list simultaneously, and it can help to make the code more readable.

Python3

num_list = [30, 200, 65, 88, 98, 500, 34]

# using enumerate() to loop over index and element
num_list = [num for i, num in enumerate(num_list) if num <= 100]

# display the list
print(num_list)
#This code is contributed by Vinay Pinjala.

Output

[30, 65, 88, 98, 34]

The time complexity of the code is O(n) as the list comprehension and enumeration loop both iterate over the entire list once, where n is the length of the input list.

The auxiliary space is also O(n) as a new list is created to store the filtered elements, which can be at most the size of the original list.

Method :using a for loop

This program removes all elements greater than a given value (100) from a list (num_list) by iterating over each element and appending the elements less than or equal to the given value to a new list (new_list). The new list is then printed.

Python3

num_list = [30, 200, 65, 88, 98, 500, 34]
value = 100

new_list = []
for num in num_list:
    if num <= value:
        new_list.append(num)

print(new_list)

Output

[30, 65, 88, 98, 34]

The time complexity of this program is O(n), where n is the length of the original list. 

The auxiliary space complexity of this program is also O(n), where n is the length of the original list.