On 04/30/2015 07:31 PM, Jon Ribbens wrote:
On 2015-04-30, Dave Angel <da...@davea.name> wrote:
Finally, I did some testing on Jon Ribben's version. His was
substantially faster for smaller sets, and about the same for 10*7. So
it's likely it'll be slower than yours and mine for 10**8.
You know what they say about assumptions. Actually, my version is six
times faster for 10**8 (running under Python 3.4).
But the real reason I didn't like it was it produced a much larger
set of happy_numbers, which could clog memory a lot sooner. For
10**7 items, I had 3250 happy members, and 19630 unhappy. And Jon
had 1418854 happy members.
Er, what? You're complaining that mine is less efficient by not
producing the wrong output?
It's not intended as a criticism; you solved a different problem. The
problem Cecil was solving was to determine if a particular number is
happy. The problem you solved was to make a list of all values under a
particular limit that are happy.
Both produce identical results for the Cecil purpose, and yours is
faster if one wants all the values. But if one wants a sampling of
values, his function will fetch them quickly, and even if you want them
all, his function will use much less memory.
He keeps only one permutation of each value in the set, for substantial
savings in space. For example, he might just keep 28, while you keep 28
and 82, 208, 280, 802, and 820.
--
DaveA
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