Saya menggunakan python 2.5 jadi saya tidak memiliki akses ke pemformatan bawaan.
Saya melihat kode Django intcomma (intcomma_recurs dalam kode di bawah) dan menyadari itu tidak efisien, karena itu rekursif dan juga menyusun regex pada setiap proses bukanlah hal yang baik juga. Ini tidak perlu menjadi 'masalah' karena Django tidak benar-benar fokus pada kinerja tingkat rendah semacam ini. Juga, saya mengharapkan faktor 10 perbedaan dalam kinerja, tetapi hanya 3 kali lebih lambat.
Karena penasaran, saya menerapkan beberapa versi intcomma untuk melihat apa keunggulan kinerja saat menggunakan regex. Data pengujian saya menyimpulkan sedikit keuntungan untuk tugas ini, tetapi tidak mengejutkan sama sekali.
Saya juga senang melihat apa yang saya duga: menggunakan pendekatan reverse xrange tidak perlu dalam kasus no-regex, tetapi itu membuat kode terlihat sedikit lebih baik dengan biaya kinerja ~ 10%.
Juga, saya menganggap apa yang Anda lewati adalah string dan terlihat agak seperti angka. Hasil tidak ditentukan sebaliknya.
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
Dan inilah hasil tesnya:
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