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Rooted by: Flatten multi-nested list
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  • Fundamentals
    Arrays
    Description

    I dont't like nesting more than 2 times, so I inverted the condition. Also, extracting the generator is more idiomatic way to convert it to list + it looks prettier for me.

     Code 
    def flatten_list(lst):
    def flatten(l):
        for i in l:
            if not isinstance(i, (list, tuple)):
                yield i
                continue
            for j in flatten_list(i):
                yield j

    return [*flatten(lst)]
     Test Cases 
    import codewars_test as test
from solution import flatten_list

@test.describe("Fixd tests")
def test_group():
    @test.it("test case 1:")
    def test_case():     
        s1 = [[0, 1, 2], [3, 4], [5, 6], [7, 8], [9]]       
        s2 = [[0, 1, 2, 3, 4], [5, 6, 7, 8], [9]]
        s3 = [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9]]
        e1 = [0, 1, 2, 3, 4, 5, 6, 7,8, 9]
        e2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
        e3 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]        
        samples = [s1, s2, s3]
        expected = [e1, e2, e3]
        for s, e in zip(samples, expected):
            test.assert_equals(flatten_list(s),e)


@test.describe("Random tests")
def test_group():
    @test.it("test case 2:")
    def test_case():     
        s1 = [[0, 1, 2], (3, 4), [5, 6], (7, 8), [9]]       
        s2 = [[0, 1, 2, 3, 4], [5, 6, 7, 8], (9)]
        s3 = [(0), [1], (2), [3], (4), [5], (6), [7], (8), [9]]
        e1 = [0, 1, 2, 3, 4, 5, 6, 7,8, 9]
        e2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
        e3 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]        
        samples = [s1, s2, s3]
        expected = [e1, e2, e3]
        for s, e in zip(samples, expected):
            test.assert_equals(flatten_list(s),e)


def test_group():
    @test.it("test case 1:")
    def test_case():     
        s1 = [0, [1, 2], 3, [4, 5], 6, [7, 8], 9]
        s2 = [0, 1, 2, [3, 4, 5], 6, 7, 8, [9]] 
        s3 = [0, [1], 2, [3], 4, [5], 6, [7], 8, [9]] 
        s4 = [0, 1, 2, [3, 4, [5], []], [6], 7, 8, [9,[]]]
        e1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
        e2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
        e3 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]   
        e4 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 
        samples = [s1, s2, s3, s4]
        expected = [e1, e2, e3, e4]
        for s, e in zip(samples, expected):
            test.assert_equals(flatten_list(s),e)
            
    @test.it("test case 2:")
    def test_case():     
        s1 = [[[[[[[[-1]]]]]]]]
        s2 = [1, 2, [3, 4, [5], ['code']], [6, [[[7, 'warz']]], 8, [[[9,[]]]]]]
        s3 = ['code', [[[[1, 2, 3], 4], 5]], 6, 7, [[], 8], [9, [[], 'warz']]]    
        e1 = [-1]        
        e2 = [1, 2, 3, 4, 5, 'code', 6, 7, 'warz',8, 9 ]
        e3 = ['code', 1, 2, 3, 4, 5, 6, 7, 8, 9, 'warz']        
        samples = [s1,s2, s3]
        expected = [e1, e2, e3]
        for s, e in zip(samples, expected):
            test.assert_equals(flatten_list(s),e)
            
@test.describe("Edge Cases")
def test_group():            
    @test.it("test case 1:")
    def test_case():     
        s1 = [0, 1, (2, 3), [[4, 5, (6, 7, (8,), [9]), 10]], (11,)]
        s2 = [0, [[[1]]], ([2, 3], [4, [[5, 6]]])]
        s3 = [1, [3], (1, 6), [[3, 8]], [[[5]]], 9, ((((2,),),),)]
        s4 =  ['eat', (0, ([1, 2, [3, [['sleep', [[4]]]]], (((6,),),), 'code', 7, [[[8]]], 9]),), 'repeat']
        e1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
        e2 = [0, 1, 2, 3, 4, 5, 6]
        e3 = [1, 3, 1, 6, 3, 8, 5, 9, 2]
        e4 = ['eat', 0, 1, 2, 3, 'sleep', 4, 6, 'code', 7, 8, 9, 'repeat']
        samples = [s1, s2, s3, s4]
        expected = [e1, e2, e3, e4]
        for s, e in zip(samples, expected):
            test.assert_equals(flatten_list(s),e)
    View Run Output
  • Code
    • def flatten_list(lst):
    • def flatten(l):
    • for i in l:
    • if isinstance(i, (list, tuple)):
    • for j in flatten_list(i):
    • yield j
    • else:
    • if not isinstance(i, (list, tuple)):
    • yield i
    • return list(flatten(lst))
    • continue
    • for j in flatten_list(i):
    • yield j
    • return [*flatten(lst)]