python – Expanding on a problem from Automate the Boring Stuff

Note: this is not the solution for the “Character Picture Grid” problem from Automate the Boring Stuff. Instead, this is an expansion of that problem simply for the sake of understanding nested loops, lists within lists, and iterating through values in order to print a picture on the screen.

Thanks to anyone who takes the time to review this. Should I comment more throughout my code so that it’s easier to read? Are there ways to shorten this program so that it could run faster? I’m still quite new to programming.

# This is an expanded version of the Character Picture Grid
# problem from Al Sweigart's book, Automate the Boring Stuff With Python.
# This function takes in user input to determine what direction to print
# the arrow.

rightArrow = (('.', '.', '.', '.', '.', '.'), 
              ('.', 'O', 'O', '.', '.', '.'),
              ('O', 'O', 'O', 'O', '.', '.'), 
              ('O', 'O', 'O', 'O', 'O', '.'),
              ('.', 'O', 'O', 'O', 'O', 'O'), 
              ('O', 'O', 'O', 'O', 'O', '.'),
              ('O', 'O', 'O', 'O', '.', '.'), 
              ('.', 'O', 'O', '.', '.', '.'),
              ('.', '.', '.', '.', '.', '.'))


def printArrow(list):
    rowLength = len(list(0))  # length of x plane coordinates
    columnLength = len(list)  # length of y plane coordinates
    print('Welcome to Arrow Pointer v1.0!')
    while True:
        #main program loop
        print('nnType in one of the following:nnup, down, left, right, or end to exit the program.')
        #user determines direction of arrow to be printed
        userInput = input()
        if userInput.lower() == 'right':
            for i in range(columnLength):
                for j in range(rowLength):
                    #first loop iterates through main list
                    #nested loop iterates through inner list elements
                    print(list(i)(j) + '     ', end='')
                print('n')

        if userInput.lower() == 'left':
            for i in range(columnLength):
                for j in range(rowLength - 1, -1, -1):
                    #iterate backwards to print arrow in opposite direction
                    print(list(i)(j) + '     ', end='')
                print('n')

        if userInput.lower() == 'down':
            for i in range(rowLength):
                for j in range(columnLength):
                    print(list(j)(i) + '     ', end='')
                print('n')

        if userInput.lower() == 'up':
            for i in range(rowLength-1, -1, -1):
                for j in range(columnLength-1, -1, -1):
                    print(list(j)(i) + '     ', end='')
                print('n')

        if userInput.lower() == 'end':
            quit()

printArrow(rightArrow)