Background: There was/is a very recent thread about ways of removing all instances of x from a list. /F proposed a list comprehension to build the result list. Given a requirement to mutate the original list, this necessitates the assignment to lst[:]. I tried a generator expression as well. However while the listcomp stayed competitive up to a million-element list, the genexp went into outer space, taking about 20 times as long. The above timeit runs show a simpler scenario where the genexp also seems to be going quadratic. Comments, clues, ... please.
Py> lc = [x for x in range(100)] Py> len(lc) 100 Py> ge = (x for x in range(100)) Py> len(ge) Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: len() of unsized object
It would be nice if unconditional ge's with known length inputs propagated __len__, but that is not currently the case. There's a similar performance glitch associated with constructing a tuple from a generator expression (with vanilla 2.4, detouring via list is actually faster)
Cheers, Nick.
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Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
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http://boredomandlaziness.skystorm.net
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