Estoy usando Python 2.5, así que no tengo acceso al formato incorporado.
Miré el código Django intcomma (intcomma_recurs en el código a continuación) y me di cuenta de que es ineficiente, porque es recursivo y también compilar la expresión regular en cada ejecución tampoco es algo bueno. Esto no es necesariamente un 'problema' ya que django no está realmente tan enfocado en este tipo de rendimiento de bajo nivel. Además, esperaba un factor de diferencia de 10 en el rendimiento, pero es solo 3 veces más lento.
Por curiosidad, implementé algunas versiones de intcomma para ver cuáles son las ventajas de rendimiento al usar regex. Los datos de mi prueba concluyen una ligera ventaja para esta tarea, pero sorprendentemente no mucho.
También me complació ver lo que sospechaba: el uso del enfoque de xrange inverso es innecesario en el caso de no regex, pero hace que el código se vea un poco mejor a un costo de ~ 10% de rendimiento.
Además, supongo que lo que está pasando es una cadena y se parece un poco a un número. Resultados indeterminados de otra manera.
from __future__ import with_statement
from contextlib import contextmanager
import re,time
re_first_num = re.compile(r"\d")
def intcomma_noregex(value):
end_offset, start_digit, period = len(value),re_first_num.search(value).start(),value.rfind('.')
if period == -1:
period=end_offset
segments,_from_index,leftover = [],0,(period-start_digit) % 3
for _index in xrange(start_digit+3 if not leftover else start_digit+leftover,period,3):
segments.append(value[_from_index:_index])
_from_index=_index
if not segments:
return value
segments.append(value[_from_index:])
return ','.join(segments)
def intcomma_noregex_reversed(value):
end_offset, start_digit, period = len(value),re_first_num.search(value).start(),value.rfind('.')
if period == -1:
period=end_offset
_from_index,segments = end_offset,[]
for _index in xrange(period-3,start_digit,-3):
segments.append(value[_index:_from_index])
_from_index=_index
if not segments:
return value
segments.append(value[:_from_index])
return ','.join(reversed(segments))
re_3digits = re.compile(r'(?<=\d)\d{3}(?!\d)')
def intcomma(value):
segments,last_endoffset=[],len(value)
while last_endoffset > 3:
digit_group = re_3digits.search(value,0,last_endoffset)
if not digit_group:
break
segments.append(value[digit_group.start():last_endoffset])
last_endoffset=digit_group.start()
if not segments:
return value
if last_endoffset:
segments.append(value[:last_endoffset])
return ','.join(reversed(segments))
def intcomma_recurs(value):
"""
Converts an integer to a string containing commas every three digits.
For example, 3000 becomes '3,000' and 45000 becomes '45,000'.
"""
new = re.sub("^(-?\d+)(\d{3})", '\g<1>,\g<2>', str(value))
if value == new:
return new
else:
return intcomma(new)
@contextmanager
def timed(save_time_func):
begin=time.time()
try:
yield
finally:
save_time_func(time.time()-begin)
def testset_xsimple(func):
func('5')
def testset_simple(func):
func('567')
def testset_onecomma(func):
func('567890')
def testset_complex(func):
func('-1234567.024')
def testset_average(func):
func('-1234567.024')
func('567')
func('5674')
if __name__ == '__main__':
print 'Test results:'
for test_data in ('5','567','1234','1234.56','-253892.045'):
for func in (intcomma,intcomma_noregex,intcomma_noregex_reversed,intcomma_recurs):
print func.__name__,test_data,func(test_data)
times=[]
def overhead(x):
pass
for test_run in xrange(1,4):
for func in (intcomma,intcomma_noregex,intcomma_noregex_reversed,intcomma_recurs,overhead):
for testset in (testset_xsimple,testset_simple,testset_onecomma,testset_complex,testset_average):
for x in xrange(1000): # prime the test
testset(func)
with timed(lambda x:times.append(((test_run,func,testset),x))):
for x in xrange(50000):
testset(func)
for (test_run,func,testset),_delta in times:
print test_run,func.__name__,testset.__name__,_delta
Y aquí están los resultados de la prueba:
intcomma 5 5
intcomma_noregex 5 5
intcomma_noregex_reversed 5 5
intcomma_recurs 5 5
intcomma 567 567
intcomma_noregex 567 567
intcomma_noregex_reversed 567 567
intcomma_recurs 567 567
intcomma 1234 1,234
intcomma_noregex 1234 1,234
intcomma_noregex_reversed 1234 1,234
intcomma_recurs 1234 1,234
intcomma 1234.56 1,234.56
intcomma_noregex 1234.56 1,234.56
intcomma_noregex_reversed 1234.56 1,234.56
intcomma_recurs 1234.56 1,234.56
intcomma -253892.045 -253,892.045
intcomma_noregex -253892.045 -253,892.045
intcomma_noregex_reversed -253892.045 -253,892.045
intcomma_recurs -253892.045 -253,892.045
1 intcomma testset_xsimple 0.0410001277924
1 intcomma testset_simple 0.0369999408722
1 intcomma testset_onecomma 0.213000059128
1 intcomma testset_complex 0.296000003815
1 intcomma testset_average 0.503000020981
1 intcomma_noregex testset_xsimple 0.134000062943
1 intcomma_noregex testset_simple 0.134999990463
1 intcomma_noregex testset_onecomma 0.190999984741
1 intcomma_noregex testset_complex 0.209000110626
1 intcomma_noregex testset_average 0.513000011444
1 intcomma_noregex_reversed testset_xsimple 0.124000072479
1 intcomma_noregex_reversed testset_simple 0.12700009346
1 intcomma_noregex_reversed testset_onecomma 0.230000019073
1 intcomma_noregex_reversed testset_complex 0.236999988556
1 intcomma_noregex_reversed testset_average 0.56299996376
1 intcomma_recurs testset_xsimple 0.348000049591
1 intcomma_recurs testset_simple 0.34600019455
1 intcomma_recurs testset_onecomma 0.625
1 intcomma_recurs testset_complex 0.773999929428
1 intcomma_recurs testset_average 1.6890001297
1 overhead testset_xsimple 0.0179998874664
1 overhead testset_simple 0.0190000534058
1 overhead testset_onecomma 0.0190000534058
1 overhead testset_complex 0.0190000534058
1 overhead testset_average 0.0309998989105
2 intcomma testset_xsimple 0.0360000133514
2 intcomma testset_simple 0.0369999408722
2 intcomma testset_onecomma 0.207999944687
2 intcomma testset_complex 0.302000045776
2 intcomma testset_average 0.523000001907
2 intcomma_noregex testset_xsimple 0.139999866486
2 intcomma_noregex testset_simple 0.141000032425
2 intcomma_noregex testset_onecomma 0.203999996185
2 intcomma_noregex testset_complex 0.200999975204
2 intcomma_noregex testset_average 0.523000001907
2 intcomma_noregex_reversed testset_xsimple 0.130000114441
2 intcomma_noregex_reversed testset_simple 0.129999876022
2 intcomma_noregex_reversed testset_onecomma 0.236000061035
2 intcomma_noregex_reversed testset_complex 0.241999864578
2 intcomma_noregex_reversed testset_average 0.582999944687
2 intcomma_recurs testset_xsimple 0.351000070572
2 intcomma_recurs testset_simple 0.352999925613
2 intcomma_recurs testset_onecomma 0.648999929428
2 intcomma_recurs testset_complex 0.808000087738
2 intcomma_recurs testset_average 1.81900000572
2 overhead testset_xsimple 0.0189998149872
2 overhead testset_simple 0.0189998149872
2 overhead testset_onecomma 0.0190000534058
2 overhead testset_complex 0.0179998874664
2 overhead testset_average 0.0299999713898
3 intcomma testset_xsimple 0.0360000133514
3 intcomma testset_simple 0.0360000133514
3 intcomma testset_onecomma 0.210000038147
3 intcomma testset_complex 0.305999994278
3 intcomma testset_average 0.493000030518
3 intcomma_noregex testset_xsimple 0.131999969482
3 intcomma_noregex testset_simple 0.136000156403
3 intcomma_noregex testset_onecomma 0.192999839783
3 intcomma_noregex testset_complex 0.202000141144
3 intcomma_noregex testset_average 0.509999990463
3 intcomma_noregex_reversed testset_xsimple 0.125999927521
3 intcomma_noregex_reversed testset_simple 0.126999855042
3 intcomma_noregex_reversed testset_onecomma 0.235999822617
3 intcomma_noregex_reversed testset_complex 0.243000030518
3 intcomma_noregex_reversed testset_average 0.56200003624
3 intcomma_recurs testset_xsimple 0.337000131607
3 intcomma_recurs testset_simple 0.342000007629
3 intcomma_recurs testset_onecomma 0.609999895096
3 intcomma_recurs testset_complex 0.75
3 intcomma_recurs testset_average 1.68300008774
3 overhead testset_xsimple 0.0189998149872
3 overhead testset_simple 0.018000125885
3 overhead testset_onecomma 0.018000125885
3 overhead testset_complex 0.0179998874664
3 overhead testset_average 0.0299999713898