Python 3 Weird print() Function Output

[straight_stewie]

To start this off: I was given a lab assignment to draw "ASCII art". The task consisted of outputting my initials, a house, and an animal. I completed the task, it has already been turned in, and graded. Neither my teacher, TA, nor myself can find a solution to the problem that is outlined below.

The goal of the program is to draw "ASCII art" to the console. I chose to use lists of lists to represent a 2 dimensional plane instead of writing a bunch of print() statements because later in the year the teacher/TA is going to break the program and make us fix it. I believe that this will be much easier to "maintain" later. Here is the code in question (sorry for no highlighting, none of the options works well with python)

 

# Initials returns a 2 dimensional array (list of lists) with the mapping for my initials. Rows = 7, Columns = 12
def Initials():

    myInitials = [[], [], [], [], [], [], [], [], [], [], [], []]

    # Initialize all sub arrays.
    for i in range(0, 7):
        for j in range(0, 12):
            myInitials[i].append(j)

    # Initialize first row.
    myInitials[0][0] = 32
    myInitials[0][1] = 95
    myInitials[0][2] = 95
    myInitials[0][3] = 95
    myInitials[0][4] = 95
    myInitials[0][5] = 95
    myInitials[0][6] = 32
    myInitials[0][7] = 32
    myInitials[0][8] = 95
    myInitials[0][9] = 95
    myInitials[0][10] = 95
    myInitials[0][11] = 32

    # Initialize second row.
    myInitials[1][0] = 32
    myInitials[1][1] = 32
    myInitials[1][2] = 32
    myInitials[1][3] = 124
    myInitials[1][4] = 32
    myInitials[1][5] = 32
    myInitials[1][6] = 32
    myInitials[1][7] = 32
    myInitials[1][8] = 124
    myInitials[1][9] = 32
    myInitials[1][10] = 124
    myInitials[1][11] = 32

    # Initialize third row.
    myInitials[2][0] = 32
    myInitials[2][1] = 32
    myInitials[2][2] = 32
    myInitials[2][3] = 124
    myInitials[2][4] = 32
    myInitials[2][5] = 32
    myInitials[2][6] = 32
    myInitials[2][7] = 32
    myInitials[2][8] = 124
    myInitials[2][9] = 32
    myInitials[2][10] = 124
    myInitials[2][11] = 32

    # Initialize fourth row.
    myInitials[3][0] = 32
    myInitials[3][1] = 32
    myInitials[3][2] = 32
    myInitials[3][3] = 124
    myInitials[3][4] = 32
    myInitials[3][5] = 32
    myInitials[3][6] = 32
    myInitials[3][7] = 32
    myInitials[3][8] = 124
    myInitials[3][9] = 95
    myInitials[3][10] = 95
    myInitials[3][11] = 95

    # Initialize fifth row.
    myInitials[4][0] = 32
    myInitials[4][1] = 32
    myInitials[4][2] = 32
    myInitials[4][3] = 124
    myInitials[4][4] = 32
    myInitials[4][5] = 32
    myInitials[4][6] = 32
    myInitials[4][7] = 32
    myInitials[4][8] = 124
    myInitials[4][9] = 32
    myInitials[4][10] = 32
    myInitials[4][11] = 124

    # Initialize sixth row.
    myInitials[5][0] = 32
    myInitials[5][1] = 32
    myInitials[5][2] = 32
    myInitials[5][3] = 124
    myInitials[5][4] = 32
    myInitials[5][5] = 32
    myInitials[5][6] = 32
    myInitials[5][7] = 32
    myInitials[5][8] = 124
    myInitials[5][9] = 32
    myInitials[5][10] = 32
    myInitials[5][11] = 124

    # Initialize seventh row.
    myInitials[6][0] = 95
    myInitials[6][1] = 95
    myInitials[6][2] = 95
    myInitials[6][3] = 47
    myInitials[6][4] = 32
    myInitials[6][5] = 32
    myInitials[6][6] = 32
    myInitials[6][7] = 32
    myInitials[6][8] = 124
    myInitials[6][9] = 95
    myInitials[6][10] = 95
    myInitials[6][11] = 124

    # Pass the jagged array back to the caller.
    return myInitials

# DrawToScreen takes a 2 dimensional array containing decimal ASCII chars and draws them to the screen
# as if it were art. All maps must be regular rectangles, with the format being myList[rows][columns]
def DrawToScreen( charMap, rows, columns ):

    for i in range(0, rows):
        for j in range(0, columns):
            print(chr(charMap[i][j]), end="")
        print("")

# testing how to print the picture to the screen. For some reason, writes "None" under all output.
print(DrawToScreen(Initials(), 7, 12))

When run, the final print() statement that calls DrawToScreen exits after writing "None" to the console, after successfully drawing the art as intended.

Come to think of it, I may have just answered my own question. Is the correct answer: By embedding the DrawToScreen function in a print statement, am I causing nested print statements, with the outer print statement having nothing to print, so prints "None"?

[ARikozuM]

Bump

 

I've been out of coding for too long to help, but hopefully this bump helps you.

[elpiop]

I believe it is because you are printing your draw DrawToScreen function. Since DrawToScreen does not return anything it ends up printing None. Which I guess is what you said, so yeah you are correct. 

[RedWulf]

I believe so, print will print the return of a function or of a whatever if given, not the actually program. Just call the function, no need to print it. 

 

Quote

def DrawToScreen( charMap, rows, columns ):

    for i in range(0, rows):
        for j in range(0, columns):
            print(chr(charMap[i][j]), end="")
        print("")

# testing how to print the picture to the screen. For some reason, writes "None" under all output.
DrawToScreen(Initials(), 7, 12)

 

 

[fizzlesticks]

1 minute ago, elpiop said:

Since DrawToScreen does not return anything it ends up printing None.

Almost. Unlike other languages, every function in Python returns something. If no return statement is hit (or a return without a value) in the function it defaults to returning None.