Python – Unique values Multiplication

Photo of Namachila Namachila Send an email 5 hours ago
0 0 4 minutes read

This article focuses on one of the operation of getting the unique list from a list that contains a possible duplicates and performing its product. This operations has large no. of applications and hence it’s knowledge is good to have. 

Method 1 : Naive method + loop In naive method, we simply traverse the list and append the first occurrence of the element in new list and ignore all the other occurrences of that particular element. The task of product is performed using loop. 

Python3




# Python 3 code to demonstrate
# Unique values Multiplication
# using naive methods + loop
 
# getting Product
def prod(val) :
    res = 1
    for ele in val:
        res *= ele
    return res 
 
# initializing list
test_list = [1, 3, 5, 6, 3, 5, 6, 1]
print ("The original list is : " + str(test_list))
 
# using naive method + loop
# Unique values Multiplication
# from list
res = []
for i in test_list:
    if i not in res:
        res.append(i)
res = prod(res)
 
# printing list after product
print ("The unique elements product : " + str(res))
 



















Output : 


The original list is : [1, 3, 5, 6, 3, 5, 6, 1]
The unique elements product : 90




Time Complexity: O(n*n), where n is the number of elements in the list “test_list”.
Auxiliary Space: O(n), where n is the number of elements in the list “test_list”.






  Method 2 : Using set() + loop This is the most popular way by which the duplicated are removed from the list. After that the product of list can be performed using loop. 




Python3


















 






 




 



























# Python 3 code to demonstrate 


# Unique values Multiplication


# using set() + loop


 


# getting Product 


def prod(val) : 


    res = 1


    for ele in val: 


        res *= ele 


    return res  


 


# initializing list


test_list = [1, 5, 3, 6, 3, 5, 6, 1]


print ("The original list is : " + str(test_list))


 


# Unique values Multiplication


# using set() + loop 


res = prod(list(set(test_list)))


 


# Unique values Multiplication


# using set() + loop


# printing result


print ("The unique elements product : " + str(res))










































Output : 


The original list is : [1, 3, 5, 6, 3, 5, 6, 1]
The unique elements product : 90




Time Complexity: O(n), where n is the number of elements in the list “test_list”.
Auxiliary Space: O(1), constant extra space required




Method #3:Using Counter() function




Python3


















 






 




 



























# Python 3 code to demonstrate


# Unique values Multiplication


from collections import Counter


# getting Product


 


 


def prod(val):


    res = 1


    for ele in val:


        res *= ele


    return res


 


 


# initializing list


test_list = [1, 5, 3, 6, 3, 5, 6, 1]


print("The original list is : " + str(test_list))


freq = Counter(test_list)


# Unique values Multiplication


uniqueValues = freq.keys()


res = prod(uniqueValues)


 


# Unique values Multiplication


# printing result


print("The unique elements product : " + str(res))










































Output


The original list is : [1, 5, 3, 6, 3, 5, 6, 1]
The unique elements product : 90




Time Complexity: O(N)


Auxiliary Space: O(N)


Method #4:Using Operator.countOf() method




Python3


















 






 




 



























# Python 3 code to demonstrate 


# Unique values Multiplication


import operator as op


 


# getting Product 


def prod(val) : 


    res = 1


    for ele in val: 


        res *= ele 


    return res  


 


# initializing list


test_list = [1, 3, 5, 6, 3, 5, 6, 1]


print ("The original list is : " + str(test_list))


 


# using naive method + loop


# Unique values Multiplication


# from list 


res = []


for i in test_list:


    if op.countOf(res,i)==0:


        res.append(i)


res = prod(res)


 


# printing list after product


print ("The unique elements product : " + str(res))










































Output




The original list is : [1, 3, 5, 6, 3, 5, 6, 1]
The unique elements product : 90




Auxiliary Space: O(N)


Time Complexity:O(N)


 Method 5 : Using numpy


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




Python3


















 






 




 



























#Using numpy approach


#Python 3 code to demonstrate


#Unique values Multiplication


import numpy as np


 


#initializing list


test_list = [1, 3, 5, 6, 3, 5, 6, 1]


print("The original list is : " + str(test_list))


 


#using numpy approach


#Unique values Multiplication


unique_list = np.unique(test_list)


result = np.prod(unique_list)


 


#printing list after product


print("The unique elements product : " + str(result))










































Output:


The original list is : [1, 3, 5, 6, 3, 5, 6, 1]The unique elements product : 90


Time Complexity: O(N)


Auxiliary Space: O(N)


Method 6 : Using List comprehension:




Python3


















 






 




 



























from functools import reduce


def prod(val) : 


    if not val:


        return 1


    return reduce(lambda x, y: x * y, val)


# initializing list


test_list = [1, 3, 5, 6, 3, 5, 6, 1]


print ("The original list is : " + str(test_list))


# using set to get unique values


# and then using list comprehension to calculate product


unique_list = list(set(test_list))


result = prod(unique_list)


# printing result


print ("The unique elements product : " + str(result))


#This code is contributed by Jyothi pinjala










































Output




The original list is : [1, 3, 5, 6, 3, 5, 6, 1]
The unique elements product : 90




Time Complexity: O(N)


Auxiliary Space: O(N)


Method 7: Using itertools groupby()




Python3


















 






 




 



























import itertools


 


# initializing list


test_list = [1, 3, 5, 6, 3, 5, 6, 1]


print ("The original list is : " + str(test_list))


 


# using groupby function from itertools library


unique_values = [key for key, group in itertools.groupby(sorted(test_list))]


 


# getting the product of the unique values


result = 1


for value in unique_values:


    result *= value


 


# printing the result


print("The unique values multiplication is:", result)


#This code is contributed by Vinay Pinjala.










































Output


The original list is : [1, 3, 5, 6, 3, 5, 6, 1]
The unique values multiplication is: 90




Time Complexity: O(N)


Auxiliary Space: O(N)








			
		


				

			

				

						
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