[EMAIL PROTECTED] wrote: > I can sort by the real parts just fine: > > >>> lst.sort(key=lambda x: x.real) > >>> pprint.pprint(lst) > [2.6000000000000001j, > 20j, > (1+2.73j), > (1+21j), > (2+2.8600000000000003j), > (2+22j), > (3+2.9900000000000002j), > (3+23j), > (4+3.1200000000000001j), > (4+24j), > (5+3.25j), > (5+25j), > (6+26j), > (6+3.3799999999999999j), > (7+27j), > (7+3.5100000000000002j), > (8+28j), > (8+3.6400000000000001j), > (9+3.77j), > (9+29j)] > > but how do I then do a secondary sort by the imaginary part, preserving the > existing ordering on the real parts? Seems like I have to resort to a > Schwartzian transform and map the complex numbers to tuples, sort that, then > map them back. With the cmp key it would have been a fairly trivial task to > define the desired compare-real-then-imag function. > > Is there a way to do this using just the key arg, no extra data structures?
Is a tuple an extra data structure? >>> lst.sort(key=lambda x: (x.real,x.imag)) >>> pprint.pprint(lst) [2.6000000000000001j, 20j, (1+2.73j), (1+21j), (2+2.8600000000000003j), (2+22j), (3+2.9900000000000002j), (3+23j), (4+3.1200000000000001j), (4+24j), (5+3.25j), (5+25j), (6+3.3799999999999999j), (6+26j), (7+3.5100000000000002j), (7+27j), (8+3.6400000000000001j), (8+28j), (9+3.77j), (9+29j)] If you don't like the tuple then just do the two sorts separately: >>> lst.sort(key=lambda x: x.imag) >>> lst.sort(key=lambda x: x.real) >>> pprint.pprint(lst) [2.6000000000000001j, 20j, (1+2.73j), (1+21j), (2+2.8600000000000003j), (2+22j), (3+2.9900000000000002j), (3+23j), (4+3.1200000000000001j), (4+24j), (5+3.25j), (5+25j), (6+3.3799999999999999j), (6+26j), (7+3.5100000000000002j), (7+27j), (8+3.6400000000000001j), (8+28j), (9+3.77j), (9+29j)] >>> -- http://mail.python.org/mailman/listinfo/python-list
