Simon Forman wrote: > Nick Craig-Wood wrote: >> Sets are pretty fast too, and have the advantage of flexibility in >> that you can put any numbers in you like >> > > I know this is self-evident to most of the people reading this, but I > thought it worth pointing out that this is a great way to test > membership in range(lo, hi, step) without doing "the necessary > algebra". > > i.e. n in set(xrange(0, 10000, 23)) ...
This is very very misleading... here are some timings : python -mtimeit "n=5000" "n in set(xrange(0,10000))" 1000 loops, best of 3: 1.32 msec per loop python -mtimeit "n=5000" "n in xrange(0,10000)" 1000 loops, best of 3: 455 usec per loop python -mtimeit "n=5000" "0 <= n < 10000" 1000000 loops, best of 3: 0.217 usec per loop sets are fast only if you create them *once* and use them again and again. even in that case, the sets use up O(n) memory. with comparison operators, you don't need extra memory *and* there is no pre-computation required. [sreeram;]
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