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Python | Multiply all numbers in the list (4 different ways)

  • Difficulty Level : Basic
  • Last Updated : 20 Oct, 2020

Given a list, print the value obtained after multiplying all numbers in a list. 
Examples: 
 

Input :  list1 = [1, 2, 3] 
Output : 6 
Explanation: 1*2*3=6 

Input : list1 = [3, 2, 4] 
Output : 24 

 

 

Method 1: Traversal

Initialize the value of the product to 1(not 0 as 0 multiplied with anything returns zero). Traverse till the end of the list, multiply every number with the product. The value stored in the product at the end will give you your final answer.
Below is the Python implementation of the above approach: 
 



Python




# Python program to multiply all values in the
# list using traversal
 
def multiplyList(myList) :
     
    # Multiply elements one by one
    result = 1
    for x in myList:
         result = result * x
    return result
     
# Driver code
list1 = [1, 2, 3]
list2 = [3, 2, 4]
print(multiplyList(list1))
print(multiplyList(list2))

Output: 
 

6
24 



 

Method 2: Using numpy.prod()

We can use numpy.prod() from import numpy to get the multiplication of all the numbers in the list. It returns an integer or a float value depending on the multiplication result.
Below is the Python3 implementation of the above approach: 
 

Python3




# Python3 program to multiply all values in the
# list using numpy.prod()
 
import numpy
list1 = [1, 2, 3]
list2 = [3, 2, 4]
 
# using numpy.prod() to get the multiplications
result1 = numpy.prod(list1)
result2 = numpy.prod(list2)
print(result1)
print(result2)

Output: 
 

6
24 

 

Method 3 Using lambda function: Using numpy.array

Lambda’s definition does not include a “return” statement, it always contains an expression that is returned. We can also put a lambda definition anywhere a function is expected, and we don’t have to assign it to a variable at all. This is the simplicity of lambda functions. The reduce() function in Python takes in a function and a list as an argument. The function is called with a lambda function and a list and a new reduced result is returned. This performs a repetitive operation over the pairs of the list.
Below is the Python3 implementation of the above approach: 
 



Python3




# Python3 program to multiply all values in the
# list using lambda function and reduce()
 
from functools import reduce
list1 = [1, 2, 3]
list2 = [3, 2, 4]
 
 
result1 = reduce((lambda x, y: x * y), list1)
result2 = reduce((lambda x, y: x * y), list2)
print(result1)
print(result2)

Output: 
 

6
24 

 

Method 4 Using prod function of math library: Using math.prod

Starting Python 3.8, a prod function has been included in the math module in the standard library, thus no need to install external libraries.
Below is the Python3 implementation of the above approach: 
 

Python3




# Python3 program to multiply all values in the
# list using math.prod
 
import math
list1 = [1, 2, 3]
list2 = [3, 2, 4]
 
 
result1 = math.prod(list1)
result2 = math.prod(list2)
print(result1)
print(result2)

Output: 
 

6
24 

 

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