On Mon, 31 Oct 2011 22:12:26 -0400, Dave Angel wrote:
> I would claim that a well-written (in C) translate function, without
> using the delete option, should be much quicker than any python loop,
> even if it does copy the data.
I think you are selling short the speed of the Python interpreter. Even
for short strings, it's faster to iterate over a string in Python 3 than
to copy it with translate:
>>> from timeit import Timer
>>> t1 = Timer('for c in text: pass', 'text = "abcd"')
>>> t2 = Timer('text.translate(mapping)',
... 'text = "abcd"; mapping = "".maketrans("", "")')
>>> min(t1.repeat())
0.450606107711792
>>> min(t2.repeat())
0.9279451370239258
> Incidentally, on the Pentium family,
> there's a machine instruction for that, to do the whole loop in one
> instruction (with rep prefix).
I'm pretty sure that there isn't a machine instruction for copying an
entire terabyte of data in one step. Since the OP explicitly said he was
checking text up to a TB in size, whatever solution is used has to scale
well.
--
Steven
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