In [27]:

    

def compact(iterable):
    curr = None
    
    for e in iterable:
        if curr is None or e != curr:
            curr = e
            yield e


    

In [28]:

    

list(compact(n**2 for n in [1, 2, 2]))


    

    
Out[28]:





[1, 4]

In [29]:

    

for i in compact(n**2 for n in [1, 2, 2]):
    print(i)


    

    




1
4

In [30]:

    

import unittest

class CompactTests(unittest.TestCase):

    """Tests for compact."""

    def assertIterableEqual(self, iterable1, iterable2):
        self.assertEqual(list(iterable1), list(iterable2))

    def test_no_duplicates(self):
        self.assertIterableEqual(compact([1, 2, 3]), [1, 2, 3])

    def test_adjacent_duplicates(self):
        self.assertIterableEqual(compact([1, 1, 2, 2, 3]), [1, 2, 3])

    def test_non_adjacent_duplicates(self):
        self.assertIterableEqual(compact([1, 2, 3, 1, 2]), [1, 2, 3, 1, 2])

    def test_lots_of_adjacent_duplicates(self):
        self.assertIterableEqual(compact([1, 1, 1, 1, 1, 1]), [1])

    def test_empty_values(self):
        self.assertIterableEqual(compact([None, 0, "", []]), [None, 0, "", []])

    def test_empty_list(self):
        self.assertIterableEqual(compact([]), [])

    # To test the Bonus part of this exercise, comment out the following line
    #@unittest.expectedFailure
    def test_accepts_iterator(self):
        nums = (n**2 for n in [1, 2, 3])
        self.assertIterableEqual(compact(nums), [1, 4, 9])

    # To test the Bonus part of this exercise, comment out the following line
    #@unittest.expectedFailure
    def test_returns_iterator(self):
        output = compact([1, 2, 3])
        self.assertEqual(iter(output), iter(output))


if __name__ == "__main__":
    unittest.main(argv=['first-arg-is-ignored'], exit=False)


    

    




........
----------------------------------------------------------------------
Ran 8 tests in 0.006s

OK

In [31]:

    

list(compact({'a': 1, 'b': 2, 'b': 1, 'b': 2}))


    

    
Out[31]:





['a', 'b']

In [ ]: