Replace multiline existing output in python

Question

In python 3 , there have been answers about how to replace an existing output with another. These answers suggest the use of end='\r' ad in print('hello', end='\r') This is working ofcourse, but it works only for one line .

In the program that I post below, I first output 5 lines which is the representation of a table matrix. The user is asked to type one number (1-3) and then the matrix is printed again with an 'X' in the position that the user indicated.

But as you can see, the matrix is printed below the initial one. How can I replace the existing output ?

If I use the end = '\r' it will just move the cursor to the beginning of the line. But this will not work for me because I want to print 5 lines , and then move the cursor to the beginning of the first line, and not to the beginning of the fifth line (as the end='\r' does).

How could I achieve this in python ?

from __future__ import print_function
list1=[' '*11,'|',' '*7,'|',' '*10] 

def board():
    print ('\t \t | \t \t |')
    print (list1)
    print ('\t \t | \t \t |')
    #print '\n'
    print

def playerone():    
    player1 = raw_input("PLAYER1: enter your position 1-3: ")
    if (player1 == '1'):
        list1[0]=' '*5 + 'X'+' '*5
    elif (player1=='2'):
        list1[2]=' '*3 + 'X'+' '*3
    elif (player1=='3'):
        list1[4]=' '*3 + 'X'+' '*6
    else:
        playerone()

print ('our board is : ')
board()

playerone()

print ('our board is :')
board()

score 0 · Answer 1 · edited May 23 '17 at 12:00

0

Unless you want to use curses (which is another big step), you cannot go back by several lines.

BUT what you can do is clear the screen and redisplay everything.

print(chr(27) + "[2J")

clears the screen

(as stated in clear terminal in python)

edited May 23 '17 at 12:00

Community

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answered Aug 18 '16 at 10:49

Jean-François Fabre

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I am using jupyter. And in python 3 this does not work. In my case at least. – spyimp Aug 18 '16 at 10:54

score 0 · Answer 2 · answered Aug 18 '16 at 10:57

You can clear the screen before printing the board.

def clearscreen(numlines=100):
"""Clear the console.
numlines is an optional argument used only as a fall-back.
"""
import os
if os.name == "posix":
    # Unix/Linux/MacOS/BSD/etc
    os.system('clear')
elif os.name in ("nt", "dos", "ce"):
    # DOS/Windows
    os.system('CLS')
else:
    # Fallback for other operating systems.
    print '\n' * numlines

And inside the board() you can call the clearscreen() to clear the screen before printing the board.

score 0 · Answer 3 · answered Aug 18 '16 at 11:21

What about trying to use a portable solution using terminal's clear command, for example:

from __future__ import print_function
import os

class Game:

    def __init__(self):
        self.running = True
        self.list1 = [' ' * 11, '|', ' ' * 7, '|', ' ' * 10]

    def clear_sceen(self):
        os.system('cls' if os.name == 'nt' else 'clear')

    def draw_board(self):
        print('our board is : ')
        print('\t \t | \t \t |')
        print(self.list1)
        print('\t \t | \t \t |')

    def check_inputs(self):
        player1 = raw_input("PLAYER1: enter your position 1-3: ")

        if (player1 not in ['1', '2', '3']):
            self.running = False
        else:
            print(chr(27) + "[2J")

            if (player1 == '1'):
                self.list1[0] = ' ' * 5 + 'X' + ' ' * 5
            elif (player1 == '2'):
                self.list1[2] = ' ' * 3 + 'X' + ' ' * 3
            elif (player1 == '3'):
                self.list1[4] = ' ' * 3 + 'X' + ' ' * 6

    def run(self):
        self.clear_sceen()

        while self.running:
            self.draw_board()
            self.check_inputs()

        print(
            '\nGame ended! you should have pressed numbers between 1-3 :P')

if __name__ == "__main__":
    g = Game()
    g.run()

Replace multiline existing output in python

3 Answers3

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