Flatten an array of arbitrarily nested arrays of integers into a flat array of integers. e.g. [[1,2,[3]],4] -> [1,2,3,4]

flatten_array.py

import unittest

#Function takes an array of arbitrarily nested arrays of int and flattens it
#into a 1 dimensional array containing the same integers.
def flatten_array(array_to_flatten):
    new_array = []
    #we check each element, if it's an INT we append it into the output arr
    #if it's not an int, we recursively call the function to flattern it
    for element in array_to_flatten:
        if type(element) is int:
            new_array.append(element)
        else:
            new_array += flatten_array(element)
    return new_array

#Test class for the created function flatten_array
class FlattenArrayTestScript(unittest.TestCase):
    def test_simple(self):
        self.assertEqual([1,2,3,4], flatten_array([1,2,3,4]))

    def test_citrusbyte(self):
        self.assertEqual([1,2,3,4], flatten_array([[1,2,[3]],4]))


if __name__=="__main__":
    unittest.main()


"""
>> python flatten_array.py

----------------------------------------------------------------------
Ran 2 tests in 0.000s

OK
"""