Need help converting a list to a string

Question

The function here just generates a random list of 0s and 1s. It's for later use in a game. So I need to take the list generated by binary_gen and convert it to a string. I've tried using .join but I just get an error message back. Is there any way for me to convert the output from binary_gen to a string? Or is there another way I can generate a random sequence of 0s and 1s?

import random

def random_binary():
    min_length = 4
    max_length = 8
    binary_gen = [random.randrange(0,2,1) for _ in range \
    (random.randint(min_length,max_length))]
    print (binary_gen)

random_binary()

Update:

import random

def random_binary():
    min_length = 4
    max_length = 8
    binary_gen = [random.randrange(0,2,1) for _ in range \
    (random.randint(min_length,max_length))]
    binary_string = "".join(binary_gen)
    print (binary_string)

random_binary()

And I get: TypeError: sequence item 0: expected str instance, int found

Please show your attempt and the error you get. [ask] - [mcve] — Julien, Jun 29 '16 at 06:16
Possible duplicate of [Python: Convert list of ints to one number?](http://stackoverflow.com/questions/489999/python-convert-list-of-ints-to-one-number) — SiHa, Jun 29 '16 at 07:19

John1024 · Answer 1 · 2016-06-29T07:00:10.930

2

To generate a random string sequence of zeroes and ones of random length from 4 to 8:

>>> from random import randint
>>> ''.join(str(randint(0, 1)) for i in range(randint(4, 8)))
'0010111'

Or, more directly:

>>> from random import choice, randint
>>> ''.join(choice('01') for i in range(randint(4, 8)))
'101101'

Counting

To count the number of 1s in a string of zeroes and ones:

>>> s = '0011100'
>>> len(s.replace('0', ''))
3

Or:

>>> sum(c=='1' for c in s)
3

edited Jun 29 '16 at 07:00

answered Jun 29 '16 at 06:22

John1024

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Thank you, that is very helpful. – kjf545 Jun 29 '16 at 06:47
@kjf545 You're welcome. Also, I added methods for counting ones. – John1024 Jun 29 '16 at 07:01

score 1 · Answer 2 · answered Jun 29 '16 at 06:19

1

import random

def random_binary(min_length=4, max_length=8):
    size = random.randint(min_length, max_length)
    return ''.join(str(random.randint(0, 1)) for _ in range(size))    

print(random_binary())

My guess is that the error you got was something like TypeError: sequence item 0: expected str instance, int found, because you were trying to join numbers instead of strings. The str(...) above is what makes this code work.

answered Jun 29 '16 at 06:19

user94559

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6
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Yup. that is the error I got. Thank you for your helpful input and answer. – kjf545 Jun 29 '16 at 06:37
My plan is to have the player guess how many 1s there are in a sequence. It'll be a simple game, but hopefully an educational one for me. I'll post it if it ends up being useful on a more broad scale. – kjf545 Jun 29 '16 at 06:38

Mikhail T. · Answer 3 · 2016-06-29T06:57:56.077

1

Please try following:

import random

def random_binary():
    min_length = 4
    max_length = 8
    binary_gen = [random.randrange(0,2,1) for _ in range \
    (random.randint(min_length,max_length))]
    _str = ''
    for i in binary_gen:
        _str += str(i)
    return _str



def count_zeros(s):
    count = 0
    for i in s:
        if i == '0':
            count += 1
    return count

It generates '111010' string. count_zeros(s) will return number of zeros in input string

edited Jun 29 '16 at 06:57

answered Jun 29 '16 at 06:23

Mikhail T.

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I gave it a try, and thank you. My plan is to take this sequence generated. Remove the zeros and get the length of the sequence afterwards. The player's job is to input how many 1s are in a sequence. I figure that isolating the ones is a good way to sort that out. – kjf545 Jun 29 '16 at 06:42
@kjf545 I va slightly modifeied you function so it would return a string isntead of a list. And i added count_zeros() function that returns nuber of zeros. Please see my edited unswer. Run `s = random_binary()` and then run `count_zeros(s)` – Mikhail T. Jun 29 '16 at 06:56

Need help converting a list to a string

3 Answers3

Counting