`set` vs `dict`

gistfile1.py

from operator import itemgetter


data = [
    {'id': 1},
    {'id': 2},
    {'id': 3},
    {'id': 4},
]

def one_line():
    return set(map(itemgetter('id'), data))


def six_lines():
    sequence_ids = {}
    for dna_molecule in data:
        id = dna_molecule['id']
        if id in sequence_ids:
            continue
        sequence_ids[id] = id
    return sequence_ids.keys()

if __name__ == '__main__':
    import timeit
    print('one_line()')
    print(timeit.timeit("one_line()", setup="from __main__ import one_line"))
    print('six_lines()')
    print(timeit.timeit("six_lines()", setup="from __main__ import six_lines"))