Alternate for range in python

Question

If I have to generate natural numbers, I can use 'range' as follows:

list(range(5))

[0, 1, 2, 3, 4]

Is there any way to achieve this without using range function or looping?

Answer 1

You could use recursion to print first n natural numbers

def printNos(n):

    if n > 0:

        printNos(n-1)
        print n

printNos(100)

Answer 2

Looping will be required in some form or another to generate a list of numbers, whether you do it yourself, use library functions, or use recursive methods.

If you're not opposed to looping in principle (but just don't want to implement it yourself), there are many practical and esoteric ways to do it (a number have been mentioned here already).

A similar question was posted here: How to fill a list. Although it has interesting solutions, they're all still looping, or using range type functions.

Answer 3

Based on Nihal's solution, but returns a list instead:

def recursive_range(n):
    if n == 0:
        return []
    return recursive_range(n-1) + [n-1]

Answer 4

Well, yes, you can do this without using range, loop or recursion:

>>> num = 10
>>> from subprocess import call
>>> call(["seq", str(num)])

You can even have a list (or a generator, of course):

>>> num = 10
>>> from subprocess import check_output
>>> ls = check_output(["seq", str(num)])
>>> [int(num) for num in ls[:-1].split('\n')]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42]

But...what's the purpose?