Question

Write the following Python script:

Imagine you live in a world without modules in Python! No numpy! No scipy! Write a Python script that defines a function called mat_mult() that takes two lists of lists as parameters and, when possible, returns a list of lists representing the matrix product of the two inputs. Your function should make sure the lists are of the appropriate size first - if not, your program should print “Invalid sizes” and return None. Note: it is actually tricky to make a useful list of zeros. For instance, if you need to start with a 5 row, 6 column double list of 0, you might be tempted to try:

'''

thing = [ [ 0 ] ∗ 6 ] ∗ 5

'''

and if you look at it in the console window, it would appear to be a 5 by 6 list of lists containing all zeros! However - try the following and see what happens:

'''

thing [ 2 ] [ 5 ]

thing

'''

Notice that the item in index 5 of every row has changed, not just the row with index 2! Given the difficulty, I will give you the line of code that will create a list of lists that is num_rows by num_cols:

'''

ans = [ [ 0 for col in range ( num_cols ) ] for row in range ( num_rows ) ]

'''

Answer 1

Hi,

As per your question, created the matrics of two lists of lists.

#------------------------------------------------------------
#do you need like this ?..means we will take input from user like first list legth 2*3 and second list leength of 3*5

list1_row= int(input("Please enter length of rows as integer value for list 1 > "))
list1_col = int(input("Please enter length of columns as integer value for list 1 > "))

list2_row = int(input("Please enter length of rows as integer value for list 2 > "))
list2_col= int(input("Please enter length of columns as integer value for list 2 > "))



if list1_col ==list2_col:
    # creating list os lists or 2D list
    list1 = ans = [ [ 0 for col in range ( list1_col ) ] for row in range ( list1_row ) ]
    list2 = ans = [ [ 0 for col in range ( list2_col ) ] for row in range ( list2_row ) ]
 # list of lists 1
    print("1. list of lists->\n")
    print(list1)
 #list of lists 2
    print("2. list of lists->\n")
    print(list2)
    #appending list2 elementsin list1
    for rw in list2:
        list1.append(rw)
    #printing matrics of 2 lists of lists
    print("2D matrics of two lists->\n")    
    print(list1)
    #printing in matrics form
    print("Matrics of two lists of lists\n")
    for row in list1: print(*row)

    
else:
    print("Please enter correct size of both lists..columns length must be same for both list to create matrics(2D array)")

Output: