Python – Matrix Custom Multiplier

Sometimes, while working with data, we can have a problem in which we need to multiply each row of matrix with a different multiplier. This kind of application is important in data science domain. Lets discuss certain ways in which this task can be performed.

Method #1 : Using loop + zip()
The combination of above functions can be used to perform this task. In this, we iterate through each row and perform the task of multiplication using zip().

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# Python3 code to demonstrate 
# Matrix Custom Multiplier
# using loop + zip()
  
# Initializing list
test_list1 = [[1, 3], [5, 6], [8, 9]]
test_list2 = [4, 3, 6]
  
# printing original lists
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
  
# Matrix Custom Multiplier
# using loop + zip()
res = []
for mul, sub in zip(test_list2, test_list1):
    temp = []
    for ele in sub:
        temp.append(mul * ele)
    res.append(temp)
  
# printing result 
print ("Matrix after custom multiplication : " + str(res))

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Output :

The original list 1 is : [[1, 3], [5, 6], [8, 9]]
The original list 2 is : [4, 3, 6]
Matrix after custom multiplication : [[4, 12], [15, 18], [48, 54]]

 

Method #2 : Using list comprehension + zip()
The combination of above methods can be used to solve this problem. In this, we just iterate through the list and perform the task of multiplication in one liner.



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# Python3 code to demonstrate 
# Matrix Custom Multiplier
# using list comprehension + zip()
  
# Initializing list
test_list1 = [[1, 3], [5, 6], [8, 9]]
test_list2 = [4, 3, 6]
  
# printing original lists
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
  
# Matrix Custom Multiplier
# using list comprehension + zip()
res =  [[mul * ele for ele in sub] for mul, sub in zip(test_list2, test_list1)]
  
# printing result 
print ("Matrix after custom multiplication : " + str(res))

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Output :

The original list 1 is : [[1, 3], [5, 6], [8, 9]]
The original list 2 is : [4, 3, 6]
Matrix after custom multiplication : [[4, 12], [15, 18], [48, 54]]

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