Am 04.10.2005 um 04:25 schrieb jepler@unpythonic.net:
As the OP suggests, decoding with a codec like mac-roman or iso8859-1 is very slow compared to encoding or decoding with utf-8. Here I'm working with 53k of data instead of 53 megs. (Note: this is a laptop, so it's possible that thermal or battery management features affected these numbers a bit, but by a factor of 3 at most)
$ timeit.py -s "s='a'*53*1024; u=unicode(s)" "u.encode('utf-8')" 1000 loops, best of 3: 591 usec per loop $ timeit.py -s "s='a'*53*1024; u=unicode(s)" "s.decode('utf-8')" 1000 loops, best of 3: 1.25 msec per loop $ timeit.py -s "s='a'*53*1024; u=unicode(s)" "s.decode('mac-roman')" 100 loops, best of 3: 13.5 msec per loop $ timeit.py -s "s='a'*53*1024; u=unicode(s)" "s.decode('iso8859-1')" 100 loops, best of 3: 13.6 msec per loop
With utf-8 encoding as the baseline, we have decode('utf-8') 2.1x as long decode('mac-roman') 22.8x as long decode('iso8859-1') 23.0x as long
Perhaps this is an area that is ripe for optimization.
For charmap decoding we might be able to use an array (e.g. a tuple (or an array.array?) of codepoints instead of dictionary. Or we could implement this array as a C array (i.e. gencodec.py would generate C code). Bye, Walter Dörwald