Thank you for those solutions so varied. Am going to have a party with them to see what works best for me.
Strange is there a way too use lousy comprehension without returning just the matching odd values? Sayth On Mon, 5 Jan 2015 5:06 AM Dan Stromberg <drsali...@gmail.com> wrote: > I'm partial to: > > #!/usr/local/cpython-3.4/bin/python > > def gen_series(top=None): > ''' > Generate the numbers from 2 to top, with alternating signs. > If top is None, generate forever. > If top is an integer, generate from 2 to top. > ''' > sign = 1 > if top is None: > number = 2 > while True: > yield number * sign > number += 1 > sign = -sign > else: > for number in range(2, top): > yield number * sign > sign = -sign > > > def main(): > list_ = list(gen_series(100)) > print(list_) > > main() > > > It's not the shortest, but it's pretty clear what's going on, and > gen_series() is reusable. > > > On Sun, Jan 4, 2015 at 3:34 AM, flebber <flebber.c...@gmail.com> wrote: > > In repsonse to this question: Write a program that prints the first 100 > members of the sequence 2, -3, 4, -5, 6, -7, 8. > > > > This is my solution it works but ugly. > > > > series = range(2,100) > > # answer = [(x,(y* -1)) for x, y in series[::2]] > > # print(answer) > > answer = [] > > for item in series: > > if item % 2 != 0: > > answer.append(item * -1) > > else: > > answer.append(item) > > > > print(answer) > > > > I know I should be better off doing this with map but cannot get it to > work. I understand also that map returns a generator so this solution > should only working in python2(correct me please if I am wrong). > > > > In [6]: map? > > Type: builtin_function_or_method > > String Form:<built-in function map> > > Namespace: Python builtin > > Docstring: > > map(function, sequence[, sequence, ...]) -> list > > > > Just getting something wrong > > list(map((lambda x: x * -1 if (x%2 != 0)), series)) > > -- > > https://mail.python.org/mailman/listinfo/python-list >
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