Creating a matrix using lists Python

Question

In Python, matrices can be created using nested lists. For example, [[1, 2], [3, 4]]. Below I have written a function that prompts the user for the dimensions of a square matrix and then prompts the user for the values in the for loop. I have a tempArray variable that temporarily stores one row of values, and then is deleted after it is appended to the matrix array. For some reason, when I print the matrix at the end, this is what I get: [ [ ], [ ] ]. What is going wrong?

def proj11_1_a():
    n = eval(input("Enter the size of the square matrix: "))
    matrix = []
    tempArray = []   

    for i in range(1, (n**2) + 1):
        val = eval(input("Enter a value to go into the matrix: "))

        if i % n == 0:
            tempArray.append(val)
            matrix.append(tempArray)
            del tempArray[:]
        else:
            tempArray.append(val)
    print(matrix)
proj11_1_a()

Answer 1

You simply delete the array elements del tempArray[:] and as lists are mutable it also clears part of matrix

def proj11_1_a():
    n = eval(input("Enter the size of the square matrix: "))
    matrix = []
    tempArray = []   

    for i in range(1, (n**2) + 1):
        val = eval(input("Enter a value to go into the matrix: "))

        if i % n == 0:
            tempArray.append(val)
            matrix.append(tempArray)
            tempArray = [] #del tempArray[:]
        else:
            tempArray.append(val)
    print(matrix)
proj11_1_a()

Which could be further simplified/cleared to

def proj11_1_a():
    # Using eval in such place does not seem a good idea
    # unless you want to accept things like "2*4-2"
    # You might also consider putting try: here to check for correctness

    n = int(input("Enter the size of the square matrix: "))
    matrix = []

    for _ in range(n): 
        row = []   

        for _ in range(n): 
            # same situation as with n
            value = float(input("Enter a value to go into the matrix: "))
            row.append(value)

        matrix.append(row)

    return matrix

Answer 2

Another solution is to change the following line:

matrix.append(tempArray)

to:

matrix.append(tempArray.copy())