micro:bit python - random library only generates one number

Question

I am making a hangman game on my microbit and am having trouble with the random library. I need to choose a random number between 1 and 7, and every single time I run the program it always yields the number '5'.The strangest part is when I copy the exact same code into a IDE like visual code studio and run in via the terminal instead of through the micro:bit emulator it creates, like I would expect, random numbers between 1 and 7

What I have tried

Attempt 1

from microbit import * #omitted when ran in terminal
import random

num = random.randint(1, 7)
display.show(str(num)) #changed to print(num) when ran in terminal

Attempt 2

from microbit import * #omitted when ran in terminal
import random

numbers = [1, 2, 3, 4, 5, 6, 7]
num = random.choice(numbers)
display.show(str(num)) #changed to print(num) when ran in terminal

Attempt 3

from microbit import * #omitted when ran in terminal
import random

random.seed(4443)
while True:
   if button_a.was_pressed:
        num = random.randint(1, 7)
        print(num)

Solution This solution only works for the physical microbit and doesn't work in the emulator.

while True:
    num = random.randint(1, 7)
    display.show(num)
    sleep(2000)
    machine.reset()

I have been following the documentation on the random library on micropython's offical docs. Is there something I am doing wrong?

Try to add random seed to your code. You can read about it in the last section of the link that you've added. — TDG, Oct 15 '22 at 08:20
Doesn't work unfortuately. Used the same example that the docs shows and it produces the same numbers (3, 4, 7, 7, ect.) — mrt, Oct 15 '22 at 21:15

score 1 · Accepted Answer · answered Oct 31 '22 at 19:09

As @Oppy correctly diagnosed, this should work correctly in the micro:bit device, and the problem only affected the Python Editor simulator. In this case the issue was that the simulator random number generator was not seeded correctly.

The micro:bit Python Editor issue has been fixed and deployed today: https://github.com/microbit-foundation/micropython-microbit-v2-simulator/issues/85

If you go to https://python.microbit.org and do a hard-refresh (to ensure the latest version is loaded), it should now work in the simulator as well as the device.

Bibhav · Answer 2 · 2022-10-15T08:19:32.220

0

Try this way:

from microbit import *
from time import sleep
import random
for i in range(10):
    display.show(str(random.randint(1, 5)))#Number to be changing
    sleep(1) #Every Second

edited Oct 15 '22 at 08:19

answered Oct 15 '22 at 08:03

Bibhav

1,579
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unfortunately it still doesn't work – mrt Oct 15 '22 at 08:05
@mrt does this version of the code make any changes? – Bibhav Oct 15 '22 at 08:23

Oppy · Answer 3 · 2022-11-01T12:53:56.467

0

Edit 1st November 2022: The bug in the simulator is now fixed. The code runs as expected on the simulator, displaying a series of random numbers.

Original reply dated 15th October 2022:

The bug appears to be in the simulator only. When I ran your code on the simulator I got the same - always the same number.

I tried using the random.seed() function, which in theory adjusts how the random numbers are generated. This has no effect in the simulator.

Downloading the code onto a micro:bit v2 produces a random number each time the reset button is pushed on the back of the micro:bit.

Interestingly, the solution proposed by Bibhav generates the same string of numbers on the simulator display. The string appears to be random, but is always be the same string of values in the same order.

Downloading Bibhav's solution to the micro:bit hardware results in what appears to be a random series of numbers that varies each time the board is reset.

edited Nov 01 '22 at 12:53

answered Oct 15 '22 at 12:03

Oppy

2,662
16
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Please put your working code as an edit to your original question so that others can benefit. – Oppy Oct 16 '22 at 13:59
machine.reset seems to freeze on the emulator. Will be updating with solution after I test with microbits. – mrt Oct 16 '22 at 20:11
We found a case where `machine.reset()` or `microbit.reset()` was freezing the simulator and fixed it as well today: https://github.com/microbit-foundation/micropython-microbit-v2-simulator/issues/86 Does that fix the issue you were encountering? Also, we haven't been able to replicate the `random.seed()` issue in the simulator (the few simple examples we've tried seem to work). If you have a way to reproduce the issue we can file it in https://github.com/microbit-foundation/micropython-microbit-v2-simulator/issues/ – carlosperate Oct 31 '22 at 19:13
The simulator now works as expected. I updated my answer to reflect this. Thanks. – Oppy Nov 01 '22 at 12:57

micro:bit python - random library only generates one number

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