How can I output a list in random order?

Question

I was writing some code for a "map chooser" and want it to cycle through maps in a line

Here's the code:

maps = ["moon", "earth", "mars", "venus", "jupiter", "saturn", "uranus", "neptune", "houses", "floodland"]
while True:
    map = random.choice(maps)
    sys.stdout.write(map)
    sys.stdout.write("\r")
    time.sleep(1)

Desired result is it cycling through all the maps in a single line, choosing a map, showing it, choosing another map, removing the other map and showing the new map in the same line and so on. What I actually get is the maps getting mixed up with each other like, I get earthland when it cycles through FloodLand and Earth.

What is the problem and how I can resolve it?

When I'm randomly choosing one item, it's supposed to cycle through them, like, "earth", "floodland", etc but what I get is earthland and other mixed up entries. And, when I mean mixed up, I mean the entries are containing text from other entries — Roy, Apr 20 '22 at 09:24

var211 · Answer 1 · 2022-04-21T16:53:18.250

1

~~If I understood your question correctly you actually need to use "\n" - line break and not "\r" carriage return. Carriage return - makes your code overwrite text every iteration.~~

Try this:

maps = ["moon", "earth", "mars", "venus", "jupiter", "saturn", "uranus", "neptune", "houses", "floodland"]
while True:
    current_map = random.choice(maps)
    sys.stdout.write(current_map)
    sys.stdout.write("\n")
    time.sleep(1)

EDIT

My modified version, another variant:

import random
import time

maps = ["moon", "earth", "mars", "venus", "jupiter", "saturn", "uranus", "neptune", "houses", "floodland"]
random.shuffle(maps)

while (rand_map := maps.pop() if maps else None):
    print('\033[2K\033[1G{}'.format(rand_map), end='\r', flush=True)
    time.sleep(1)

edited Apr 21 '22 at 16:53

answered Apr 20 '22 at 09:33

var211

596
5
10

You are using the \n linebreak, it shows everything in a newline. This not what I want. I want it to choose a map, show it, and choose another map, remove the old map, show the new map and so on. – Roy Apr 20 '22 at 09:52
I see, sorry for the not relevant answer. Made another variant just for the record and for fun. – var211 Apr 21 '22 at 16:46

score 0 · Answer 2 · answered Apr 20 '22 at 09:42

0

from random import randint

map_length= len(maps)

for _ in range(map_length):
    index = int(randint(0,map_length))
    print(maps[index])

answered Apr 20 '22 at 09:42

med sabkhi

1
1

Deusy94 · Accepted Answer · 2022-04-20T10:26:38.350

The problem arise when using sys.stdout.write("\r"). You are basically telling the program to go at the beginning of the line and write the new map from there. When you wrote a longer map before you have some leftovers character at the end when writing a new one.

The fix really depends on the terminal you're printing on. If you can afford an additional variable this solution should work almost everywhere:

maps = ["moon", "earth", "mars", "venus", "jupiter", "saturn", "uranus", "neptune", "houses", "floodland"]
last_print_len = 0
while True:
    current_map = random.choice(maps)
    empty = last_print_len - len(current_map) if last_print_len > len(current_map) else 0
    sys.stdout.write(current_map + " " * empty + "\r")
    last_print_len = len(maps)
    time.sleep(1)

If not, you can try something like:

maps = ["moon", "earth", "mars", "venus", "jupiter", "saturn", "uranus", "neptune", "houses", "floodland"]
while True:
    current_map = random.choice(maps)
    sys.stdout.write('\033[2K\033[1G')    # Erase and go at the beginning of line  
    sys.stdout.write(current_map + "\r")
    time.sleep(1)

How can I output a list in random order?

3 Answers3

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