Python – Remove Negative Elements in List
Sometimes, while working with Python lists, we can have a problem in which we need to remove all the negative elements from list. This kind of problem can have application in many domains such as school programming and web development. Let’s discuss certain ways in which this task can be performed.
Input : test_list = [6, 4, 3] Output : [6, 4, 3] Input : test_list = [-6, -4] Output : []
Method #1 : Using list comprehension The combination of above functions can be used to solve this problem. In this, we perform the task of removing negative elements by iteration in one liner using list comprehension
Python3
# Python3 code to demonstrate working of # Remove Negative Elements in List # Using list comprehension # initializing list test_list = [ 5 , 6 , - 3 , - 8 , 9 , 11 , - 12 , 2 ] # printing original list print ("The original list is : " + str (test_list)) # Remove Negative Elements in List # Using list comprehension res = [ele for ele in test_list if ele > 0 ] # printing result print (" List after filtering : " + str (res)) |
The original list is : [5, 6, -3, -8, 9, 11, -12, 2] List after filtering : [5, 6, 9, 11, 2]
Method #2 : Using filter() + lambda The combination of above functions can also offer an alternative to this problem. In this, we extend logic of retaining positive formed using lambda function and extended using filter().
Python3
# Python3 code to demonstrate working of # Remove Negative Elements in List # Using filter() + lambda # initializing list test_list = [ 5 , 6 , - 3 , - 8 , 9 , 11 , - 12 , 2 ] # printing original list print ("The original list is : " + str (test_list)) # Remove Negative Elements in List # Using filter() + lambda res = list ( filter ( lambda x : x > 0 , test_list)) # printing result print (" List after filtering : " + str (res)) |
The original list is : [5, 6, -3, -8, 9, 11, -12, 2] List after filtering : [5, 6, 9, 11, 2]
Method #3: Using list(),map(),startswith() methods
Python3
# Python3 code to demonstrate working of # Remove Negative Elements in List # initializing list test_list = [ 5 , 6 , - 3 , - 8 , 9 , 11 , - 12 , 2 , 0 ] # printing original list print ( "The original list is : " + str (test_list)) # Remove Negative Elements in List x = list ( map ( str ,test_list)) res = [] for i in range ( 0 , len (x)): if ( not x[i].startswith( "-" ) and x[i]! = "0" ): res.append(test_list[i]) # printing result print ( "List after filtering : " + str (res)) |
The original list is : [5, 6, -3, -8, 9, 11, -12, 2] List after filtering : [5, 6, 9, 11, 2]
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