Write a Python program to search whether a given element is present in a list or not
Check if element exists in list in PythonList is an important container in python as if stores elements of all the datatypes as a collection. Knowledge of certain list operations is necessary for day-day programming. This article discusses one of the basic list operations of ways to check the existence of elements in the list. Show
Method 1: Naive MethodIn Naive method, one easily uses a loop that iterates through all the elements to check the existence of the target element. This is the simplest way to check the existence of the element in the list. Method 2: Using inPython is the most conventional way to check if an element exists in a list or not. This particular way returns True if an element exists in the list and False if the element does not exist in the list. List need not be sorted to practice this approach of checking. Code #1: Demonstrating to check the existence of an element in the list using the Naive method and in. Python3
Output : Checking if 4 exists in list ( using loop ) : Element Exists Checking if 4 exists in list ( using in ) : Element Exists Method 3 : Using set() + inConverting the list into the set and then using in can possibly be more efficient than only using in. But having efficiency for a plus also has certain negatives. One among them is that the order of list is not preserved, and if you opt to take a new list for it, you would require to use extra space. Another drawback is that set disallows duplicity and hence duplicate elements would be removed from the original list. Method 4 : Using sort() + bisect_left()The conventional binary search way of testing element existence, hence list has to be sorted first and hence not preserving the element ordering. bisect_left() returns the first occurrence of the element to be found and has worked similarly to lower_bound() in C++ STL.
Code #2 : Demonstrating to check existence of element in list using set() + in and sort() + bisect_left(). Python3
Method 5 : Using count()We can use the in-built python List method, count(), to check if the passed element exists in List. If the passed element exists in the List, count() method will show the number of times it occurs in the entire list. If it is a non-zero positive number, it means an element exists in the List. Code #3 : Demonstrating to check the existence of elements in the list using count(). Python3
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Python: Check if Element Exists in ListIn python, list is a collections of data-types, which is used to store all the data types. In this tutorial we will learn in python, how to check if an item, element, number, value, object, word exists in the list? 1. Using “in” OperatorIn this example, we are using ‘in’ operator to check if an item or element exists in a sequence or not. If an item exists in the list, it will return the output is true, elseit returnsfalse. Example: # Python3 code # Check if element exists in the list # Using in Operator # Initialization of list MyList = ['a','b','c','d','e'] # Print list print("Our List: ", MyList) # Check if 'b' exists in the list or not if 'b' in MyList: print(" Item 'b' is present in the list") else: Print(" Item 'b' is not present in the list")Output: Our List:['a','b','c','d','e'] Item 'b' is present in the listExecution Time: 0.0009 (Seconds) Explanation: In the above example, we used the ‘in’ operator to check whether ‘b’ exists in MyList or not. We used the if-else condition to print the result. Since ‘b’ is present in the list, the ifblock is executed. If ‘b’ was not present in MyList the elseblock would have been executed. Python Program to check if element exists in listIn this tutorial, we will learn how to check if an element is present in a list or not. List is an ordered set of values enclosed in square brackets [ ]. List stores some values called elements in it, which can be accessed by their particular index. We will be discussing the various approaches by which we can check for an element in the given list. The program will accept the list and the element which has to check, it should return True if it exists else, it will return False Input: [6, 22, 7, 3, 0, 11] element= 0 Output: True Let us look at the different approaches we can follow to execute the task. Python program to check if an element is present in listHere, we will write a Python program to check whether the specified element is present in the list or not. Python programming language is a high-level and object-oriented programming language. Python is an easy to learn, powerful high-level programming language. It has a simple but effective approach to object-oriented programming. List is a sequence data type. It is mutable as its values in the list can be modified. It is a collection of ordered sets of values enclosed in square brackets []. Check if an element is present in the list We will take a list as input from the user and then ask the user to enter the element's value to be searched. Then we will return YES/NO based on whether the element is present in the list or not. Example: Input: [4, 2, 9, 5, 1, 0, 7] element -> 5 Output: PresentPython provides us multiple ways to perform the tasks. And to check for an element's presence also, we can use multiple ways in which the present can be check. Method 1: Searching technique To check whether an element is present in a list or not. We can simply use any searching technique and find the element in the list. Here, we will discept linear search.
Program to check if an element is present in the list # Python program to check if an # element exists in list # Getting list from user myList = [] length = int(input("Enter number of elements: ")) for i in range(0, length): value = int(input()) myList.append(value) ele = int(input("Enter element to be searched in the list: ")) # checking for the presence of element in list found = False for i in myList: if(i == ele) : found = True break if(found): print("Element found") else : print("Element not found!")Output: Enter number of elements: 5 2 6 8 4 1 Enter element to be searched in the list: 4 Element foundMethod 2: Using in operator Python programming language provides us an operator "in" to check whether an element is present in a list. Syntax: Returns boolean values based on the presence of element in the list. Algorithm:
Program to check if an element is present in a list using in operator # Python program to check if an element # exists in list # Getting list from user myList = [] length = int(input("Enter number of elements: ")) for i in range(0, length): value = int(input()) myList.append(value) ele = int(input("Enter element to be searched in the list: ")) # checking for the presence of element in list if(ele in myList): print("Element found") else : print("Element not found!")Output: Enter number of elements: 5 10 20 30 40 50 Enter element to be searched in the list: 30 Element foundMethod 3: Using bisect_left() method on sorted list The list needs to be sorted in order to apply this method. The bisect_left() method find's and returns the first occurrence of the given element in a sorted array. Syntax: For sorting list list_name.sort() bisect_left method : bisect_left(list, element)Returns a boolean value based on whether the element is present in the list or not. Program to check if an element is present in list # Python program to check if an element # exists in list import bisect # Getting list from user myList = [] length = int(input("Enter number of elements: ")) for i in range(0, length): value = int(input()) myList.append(value) ele = int(input("Enter element to be searched in the list: ")) # checking for the presence of element in list myList.sort() if(bisect.bisect_left(myList, ele) ): print("Element found") else : print("Element not found!")Output: Enter number of elements: 5 10 12 15 20 25 Enter element to be searched in the list: 25 Element foundPython List Programs » How to find the length of a list in Python (3 effective ways)? Python program to swap any two elements in the list ADVERTISEMENT Preparation Aptitude Questions MCQs Find Output Programs What's New
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Comments and Discussions! Please enable JavaScript to view the comments powered by Disqus. ADVERTISEMENT Python List Contains: How to Check If Item Exists in ListDuring development in Machine learning, AI, or even web development, we generally come across a problem where we need to test if the particular item from a given list lies as a sub-string or not. To check if the list contains the specific element or not in Python, use the“in”operator or“not in” operator. Let’s explore this topic in detail. Check if element exists in list using python “in” OperatorCondition to check if element is in List : It will return True, if element exists in list else return false. For example check if ‘at’ exists in list i.e. Condition to check if element is not in List : ''' check if element NOT exist in list using 'in' ''' if 'time' not in listOfStrings : print("Yes, 'time' NOT found in List : " , listOfStrings) Advertisements Python Program to Search an Element in a ListThis article deals with some programs in Python that searches an element in a list. Here both element and list must be entered by user at run-time. Here are the list of programs covered in this article:
Python Check If List Item Exists
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Check If List Item ExistsTo determine if a specified item is present in a list use the in keyword: ExampleCheck if "apple" is present in the list:
thislist = ["apple", "banana", "cherry"]
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