[Tutor] clean text

[Kent Johnson]

On Tue, May 19, 2009 at 1:19 PM, spir <denis.spir at free.fr> wrote:
> Thank you Albert, Kent, Sanders, Lie, Malcolm.
>
> This time regex wins! Thought it wouldn't because of the additional func call (too bad we cannot pass a mapping to re.sub). Actually the diff. is very small ;-) The relevant  change is indeed using a dict.

The substChar() function is only called when a control character is
found, so the relative time between the regex version and the next
best will depend on the character mix. Your random strings seem a bit
heavy on control chars.

My guess is that the reason regex is a win is because it gets rid of
the explicit Python-coded loop.

> Replacing string concat with ''.join() is slower (tested with 10 times and 100 times bigger strings too). Strange...
> Membership test in a set is only very slightly faster than in dict keys.

String concatenation has been optimized for this use case in recent
versions of Python.

Kent