Python | Check if list contains all unique elements
Some list operations require us to check if all the elements in the list are unique. This usually happens when we try to perform the set operations in a list. Hence this particular utility is essential at these times. Lets discuss certain methods by which this can be performed.
Method #1 : Naive Method
Solutions usually start from the simplest method one can apply to perform a particular task. Here you can use a nested loop to check if after that element similar element exists in the remaining list.
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# Python3 code to demonstrate
# to test all elements in list are unique
# using naive method
# initializing list
test_list = [1, 3, 4, 6, 7]
# printing original list
print ["The original list is : " + str[test_list]]
flag = 0
# using naive method
# to check all unique list elements
for i in range[len[test_list]]:
for i1 in range[len[test_list]]:
if i != i1:
if test_list[i] == test_list[i1]:
flag = 1
# printing result
if[not flag] :
print ["List contains all unique elements"]
else :
print ["List contains does not contains all unique elements"]
|
Output :
The original list is : [1, 3, 4, 6, 7] List contains all unique elementsMethod #2 : Using len[] + set[]
This is most elegant way in which this problem can be solved by using just a single line. This solution converts the list to set and then tests with original list if contains similar no. of elements.
|
# Python3 code to demonstrate
# to test all elements in list are unique
# using set[] + len[]
# initializing list
test_list = [1, 3, 4, 6, 7]
# printing original list
print ["The original list is : " + str[test_list]]
flag = 0
# using set[] + len[]
# to check all unique list elements
flag = len[set[test_list]] == len[test_list]
# printing result
if[flag] :
print ["List contains all unique elements"]
else :
print ["List contains does not contains all unique elements"]
|
Output :
The original list is : [1, 3, 4, 6, 7] List contains all unique elements
Method #3 : Using Counter.itervalues[]
This is one of the different methods and uses the frequency obtained of all the elements using Counter, and checks if any of the frequency is greater than 1.
|
# Python code to demonstrate
# to test all elements in list are unique
# using Counter.itervalues[]
from collections import Counter
# initializing list
test_list = [1, 3, 4, 6, 7]
# printing original list
print ["The original list is : " + str[test_list]]
flag = 0
# using Counter.itervalues[]
# to check all unique list elements
counter = Counter[test_list]
for values in counter.itervalues[]:
if values > 1:
flag = 1
# printing result
if[not flag] :
print ["List contains all unique elements"]
else :
print ["List contains does not contains all unique elements"]
|
Output :
The original list is : [1, 3, 4, 6, 7] List contains all unique elementsAttention 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
Python | Check if all elements in a List are same
Given a list, write a Python program to check if all the elements in given list are same.
Example:
Input: ['Geeks', 'Geeks', 'Geeks', 'Geeks', ] Output: Yes Input: ['Geeks', 'Is', 'all', 'Same', ] Output: NoThere are various ways we can do this task. Let’s see different ways we can check if all elements in a List are same.
Method #1: Comparing each element.
|
# Python program to check if all
# ments in a List are same
def ckeckList[lst]:
ele = lst[0]
chk = True
# Comparing each element with first item
for item in lst:
if ele != item:
chk = False
break;
if [chk == True]: print["Equal"]
else: print["Not equal"]
# Driver Code
lst = ['Geeks', 'Geeks', 'Geeks', 'Geeks', ]
ckeckList[lst]
|
Output:
Equal
But In Python, we can do the same task in much interesting ways.
Method #2: Using all[] method
|
# Python program to check if all
# elements in a List are same
res = False
def chkList[lst]:
if len[lst] < 0 :
res = True
res = all[ele == lst[0] for ele in lst]
if[res]:
print["Equal"]
else:
print["Not equal"]
# Driver Code
lst = ['Geeks', 'Geeks', 'Geeks', 'Geeks']
chkList[lst]
|
Output:
Equal
Method #3: Using count[] method
|
# Python program to check if all
# elements in a List are same
res = False
def chkList[lst]:
if len[lst] < 0 :
res = True
res = lst.count[lst[0]] == len[lst]
if[res]:
print["Equal"]
else:
print["Not equal"]
# Driver Code
lst = ['Geeks', 'Geeks', 'Geeks', 'Geeks']
chkList[lst]
|
Output:
Equal
Method #4: Using set data structure
Since we know there cannot be duplicate elements in a set, we can use this property to check whether all the elements are same or not.
|
# Python program to check if all
# elements in a List are same
def chkList[lst]:
return len[set[lst]] == 1
# Driver Code
lst = ['Geeks', 'Geeks', 'Geeks', 'Geeks']
if chkList[lst] == True: print["Equal"]
else: print["Not Equal"]
|
Output:
EqualAttention 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
Check if list1 contains all elements of list2 using all[]
''' check if list1 contains all elements in list2 ''' result = all[elem in list1 for elem in list2] if result: print["Yes, list1 contains all elements in list2"] else : print["No, list1 does not contains all elements in list2"Python all[] function checks if all Elements of given Iterable is True.So, convert the list2 to Iterable and for each element in Iterable i.e. list2 check if element exists in list1.
check if element are same using all[]
Let’s convert the list to Iterable and check if each entry of iterable is equal to first element of list using all[] i.e.
Check if list contains all unique elements in Python
A list in python can contain elements all of which may or may not be unique. But for a scenario when we need unique elements like marking the attendance for different roll numbers of a class. Below is the approaches with can use.
Python - Check if all elements in a List are same
Sometimes we come across the need to check if we have one single value repeated in a list as list elements. We can check for such scenario using the below python programs. There are different approaches.
Python – Check if all elements in a List are the same
In this tutorial, we are going to see different ways to check if all the items in a given list are the same.
- Using Set
- Using all[] method
- Using count[] method
Set is a type of collection in Python, just like list and tuple. Set is different because the elements do not have duplicates, unlike list and tuple. All the elements of the set are unique.
Here is a simple program with which you can check if all the items in the list are the same.
listOfColor = ['blue','blue','blue','blue'] if[len[set[listOfColor]]==1]: print["All items in the list are the same"] else: print["All items in the list are not the same"]Output:
All items in the list are the sameCheck if all elements in a List are the same using all[] methodThe all[] function is a function that takes an iterable as input and returns “true” if all elements of that input are “true”. Otherwise, “false”.
The easiest way is to check if all the items in the list are the same as the first item in the list.
listOfColor = ['blue','blue','blue','blue'] if all[x == listOfColor[0] for x in listOfColor]: print["All items in the list are the same"] else: print["All items in the list are not the same"]Output:
All items in the list are the sameCheck if all elements in a List are the same using count[] methodcount[] returns the number of occurrences of a given item in the list.
We call the count[] function on the list with the first element of the list as an argument. If its number of occurrences is equal to the length of the list, it means that all the elements of the list are the same.
listOfColor = ['blue','blue','blue','blue'] if listOfColor.count[listOfColor[0]] == len[listOfColor]: print["All items in the list are the same"] else: print["All items in the list are not the same"]Output:
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