问题
I need to convert a string in the format "1.234.345,00" to the float value 1234345.00.
One way is to use repeated str.replace:
x = "1.234.345,00"
res = float(x.replace('.', '').replace(',', '.'))
print(res, type(res))
1234345.0 <class 'float'>
However, this appears manual and non-generalised. This heavily upvoted answer suggests using the locale library. But my default locale doesn't have the same conventions as my input string. I then discovered a way to extract the characters used in local conventions as a dictionary:
import locale
print(locale.localeconv())
{'int_curr_symbol': '', 'currency_symbol': '', 'mon_decimal_point': '',
..., 'decimal_point': '.', 'thousands_sep': '', 'grouping': []}
Is there a way to update this dictionary, save as a custom locale and then be able to call this custom locale going forwards. Something like:
mylocale = locale.create_new_locale() # "blank" conventions or copied from default
mylocale.localeconv()['thousands_sep'] = '.'
mylocale.localeconv()['decimal_point'] = ','
setlocale(LC_NUMERIC, mylocale)
atof('123.456,78') # 123456.78
If this isn't possible, how do we get a list of all available locale and their conventions? Seems anti-pattern to "deduce" the correct configuration from the conventions (not to mention inefficient / manual), so I was hoping for a generic solution such as above pseudo-code.
Edit: Here's my attempt at finding all locales where thousands_sep == '.' and decimal_point == ','. In fact, more generally, to group locales by combinations of these parameters:
import locale
from collections import defaultdict
d = defaultdict(list)
for alias in locale.locale_alias:
locale.setlocale(locale.LC_ALL, alias)
env = locale.localeconv()
d[(env['thousands_sep'], env['decimal_point'])].append(alias)
Result:
---------------------------------------------------------------------------
Error Traceback (most recent call last)
<ipython-input-164-f8f6a6db7637> in <module>()
5
6 for alias in locale.locale_alias:
----> 7 locale.setlocale(locale.LC_ALL, alias)
8 env = locale.localeconv()
9 d[(env['thousands_sep'], env['decimal_point'])].append(alias)
C:\Program Files\Anaconda3\lib\locale.py in setlocale(category, locale)
596 # convert to string
597 locale = normalize(_build_localename(locale))
--> 598 return _setlocale(category, locale)
599
600 def resetlocale(category=LC_ALL):
Error: unsupported locale setting
回答1:
If you pop open the source code for locale, you can see that there is a variable called _override_localeconv (which seems to be for testing purposes).
# With this dict, you can override some items of localeconv's return value.
# This is useful for testing purposes.
_override_localeconv = {}
Trying the following does seem to override the dictionary without changing the entire locale, though it probably has some unintended consequences, especially since changing locales isn't threadsafe. Be careful!
import locale
locale._override_localeconv["thousands_sep"] = "."
locale._override_localeconv["decimal_point"] = ","
print locale.atof('123.456,78')
Try it online!
回答2:
Here's something, using Babel, that works for me.
First you feed it some test data, with your expectations and it builds a dictionary of separator to locale alias that fits.
Then you can convert from that point on.
import string
from decimal import Decimal
from babel.numbers import parse_decimal, NumberFormatError
from babel.core import UnknownLocaleError
import locale
traindata = [
("1.234.345,00", Decimal("1234345.00")),
("1,234,345.00", Decimal("1234345.00")),
("345", Decimal("345.00")),
]
data = traindata + [
("345,00", Decimal("345.00")),
("345.00", Decimal("345.00")),
("746", Decimal("746.00")),
]
def findseps(input_):
#you need to have no separator
#or at least a decimal separator for this to work...
seps = [c for c in input_ if not c in string.digits]
if not seps:
return ""
sep = seps[-1]
#if the decimal is something then thousand will be the other...
seps = "." + sep if sep == "," else "," + sep
return seps
def setup(input_, exp, lookup):
key = findseps(input_)
if key in lookup:
return
for alias in locale.locale_alias:
#print(alias)
try:
got = parse_decimal(input_, locale=alias)
except (NumberFormatError,UnknownLocaleError, ValueError) as e:
continue
except (Exception,) as e:
raise
if exp == got:
lookup[key] = alias
return
def convert(input_, lookup):
seps = findseps(input_)
try:
locale_ = lookup[seps]
convert.locale_ = locale_
except (KeyError,) as e:
convert.locale_ = None
return "unexpected seps:%s" % seps
try:
return parse_decimal(input_, locale=locale_)
except (Exception,) as e:
return e
lookup = {}
#train your data
for input_, exp in traindata:
setup(input_, exp, lookup)
#once it's trained you know which locales to use
print(data)
for input_, exp in data:
got = convert(input_, lookup)
# print (input_)
msg = "%s => %s with local:%s:" % (input_, got, convert.locale_)
if exp == got:
print("\n success : " + msg)
else:
print("\n failure : " + msg)
print(lookup)
output:
[('1.234.345,00', Decimal('1234345.00')), ('1,234,345.00', Decimal('1234345.00')), ('345', Decimal('345.00')), ('345,00', Decimal('345.00')), ('345.00', Decimal('345.00')), ('746', Decimal('746.00'))]
success : 1.234.345,00 => 1234345.00 with local:is_is:
success : 1,234,345.00 => 1234345.00 with local:ko_kr.euc:
success : 345 => 345 with local:ko_kr.euc:
success : 345,00 => 345.00 with local:is_is:
success : 345.00 => 345.00 with local:ko_kr.euc:
success : 746 => 746 with local:ko_kr.euc:
{',.': 'ko_kr.euc', '': 'ko_kr.euc', '.,': 'is_is'}
回答3:
There are two parts in your question:
- How can I parse '1.234.345,00' in a generic way?
- How can I easily find the locale associated to '1.234.345,00'?
You can use the amazing Babel library for both.
How can I parse '1.234.345,00' in a generic way?
One locale associated with a . thousands separator and a , decimal separator is ger_de, for German.
To parse it, simply use
>>> from babel.numbers import parse_decimal
>>> parse_decimal('1.234.345,00', locale='ger_de')
Decimal('1234345.00')
How can I easily find the locale associated to '1.234.345,00'?
Use this routine which checks the string to parse against the expected value for all locales, and returns the ones that are compatible:
import locale
from babel.numbers import parse_decimal
from decimal import Decimal
def get_compatible_locales(string_to_parse, expected_decimal):
compatible_aliases = []
for alias in locale.locale_alias:
try:
parsed_decimal = parse_decimal(string_to_parse, locale=alias)
if parsed_decimal == expected_decimal:
compatible_aliases.append(alias)
except Exception:
continue
return compatible_aliases
For your example:
>>> print(get_compatible_locales('1.234.345,00', Decimal('1234345')))
['ar_dz', 'ar_lb', 'ar_ly', 'ar_ma', 'ar_tn', 'ast_es', 'az', 'az_az', 'az_az.iso88599e', 'bs', 'bs_ba', 'ca', 'ca_ad', 'ca_es', 'ca_es@valencia', 'ca_fr', 'ca_it', 'da', 'da_dk', 'de', 'de_at', 'de_be', 'de_de', 'de_lu', 'el', 'el_cy', 'el_gr', 'el_gr@euro', 'en_be', 'en_dk', 'es', 'es_ar', 'es_bo', 'es_cl', 'es_co', 'es_ec', 'es_es', 'es_py', 'es_uy', 'es_ve', 'eu', 'eu_es', 'fo', 'fo_fo', 'fr_lu', 'fy_nl', 'ger_de', 'gl', 'gl_es', 'hr', 'hr_hr', 'hsb_de', 'id', 'id_id', 'in', 'in_id', 'is', 'is_is', 'it', 'it_it', 'kl', 'kl_gl', 'km_kh', 'lb_lu', 'lo', 'lo_la', 'lo_la.cp1133', 'lo_la.ibmcp1133', 'lo_la.mulelao1', 'mk', 'mk_mk', 'nl', 'nl_aw', 'nl_be', 'nl_nl', 'ps_af', 'pt', 'pt_br', 'ro', 'ro_ro', 'rw', 'rw_rw', 'sl', 'sl_si', 'sr', 'sr@cyrillic', 'sr@latn', 'sr_cs', 'sr_cs.iso88592@latn', 'sr_cs@latn', 'sr_me', 'sr_rs', 'sr_rs@latn', 'sr_yu', 'sr_yu.cp1251@cyrillic', 'sr_yu.iso88592', 'sr_yu.iso88595', 'sr_yu.iso88595@cyrillic', 'sr_yu.microsoftcp1251@cyrillic', 'sr_yu.utf8', 'sr_yu.utf8@cyrillic', 'sr_yu@cyrillic', 'tr', 'tr_cy', 'tr_tr', 'vi', 'vi_vn', 'vi_vn.tcvn', 'vi_vn.tcvn5712', 'vi_vn.viscii', 'vi_vn.viscii111', 'wo_sn']
Bonus: How can I have a human-readable version of these locales?
Use the following routine, where my_locale should be your own locale:
from babel import Locale
def get_display_name(alias, my_locale='en_US'):
l = Locale.parse(alias)
return l.get_display_name(my_locale)
You can then use it this way:
>>> print({loc: get_display_name(loc) for loc in locales})
{'ar_dz': 'Arabic (Algeria)', 'ar_lb': 'Arabic (Lebanon)', 'ar_ly': 'Arabic (Libya)', 'ar_ma': 'Arabic (Morocco)', 'ar_tn': 'Arabic (Tunisia)', 'ast_es': 'Asturian (Spain)', 'az': 'Azerbaijani', 'az_az': 'Azerbaijani (Latin, Azerbaijan)', 'az_az.iso88599e': 'Azerbaijani (Latin, Azerbaijan)', 'bs': 'Bosnian', 'bs_ba': 'Bosnian (Latin, Bosnia & Herzegovina)', 'ca': 'Catalan', 'ca_ad': 'Catalan (Andorra)', 'ca_es': 'Catalan (Spain)', 'ca_es@valencia': 'Catalan (Spain)', 'ca_fr': 'Catalan (France)', 'ca_it': 'Catalan (Italy)', 'da': 'Danish', 'da_dk': 'Danish (Denmark)', 'de': 'German', 'de_at': 'German (Austria)', 'de_be': 'German (Belgium)', 'de_de': 'German (Germany)', 'de_lu': 'German (Luxembourg)', 'el': 'Greek', 'el_cy': 'Greek (Cyprus)', 'el_gr': 'Greek (Greece)', 'el_gr@euro': 'Greek (Greece)', 'en_be': 'English (Belgium)', 'en_dk': 'English (Denmark)', 'es': 'Spanish', 'es_ar': 'Spanish (Argentina)', 'es_bo': 'Spanish (Bolivia)', 'es_cl': 'Spanish (Chile)', 'es_co': 'Spanish (Colombia)', 'es_ec': 'Spanish (Ecuador)', 'es_es': 'Spanish (Spain)', 'es_py': 'Spanish (Paraguay)', 'es_uy': 'Spanish (Uruguay)', 'es_ve': 'Spanish (Venezuela)', 'eu': 'Basque', 'eu_es': 'Basque (Spain)', 'fo': 'Faroese', 'fo_fo': 'Faroese (Faroe Islands)', 'fr_lu': 'French (Luxembourg)', 'fy_nl': 'Western Frisian (Netherlands)', 'ger_de': 'German (Germany)', 'gl': 'Galician', 'gl_es': 'Galician (Spain)', 'hr': 'Croatian', 'hr_hr': 'Croatian (Croatia)', 'hsb_de': 'Upper Sorbian (Germany)', 'id': 'Indonesian', 'id_id': 'Indonesian (Indonesia)', 'in': 'Indonesian (Indonesia)', 'in_id': 'Indonesian (Indonesia)', 'is': 'Icelandic', 'is_is': 'Icelandic (Iceland)', 'it': 'Italian', 'it_it': 'Italian (Italy)', 'kl': 'Kalaallisut', 'kl_gl': 'Kalaallisut (Greenland)', 'km_kh': 'Khmer (Cambodia)', 'lb_lu': 'Luxembourgish (Luxembourg)', 'lo': 'Lao', 'lo_la': 'Lao (Laos)', 'lo_la.cp1133': 'Lao (Laos)', 'lo_la.ibmcp1133': 'Lao (Laos)', 'lo_la.mulelao1': 'Lao (Laos)', 'mk': 'Macedonian', 'mk_mk': 'Macedonian (Macedonia)', 'nl': 'Dutch', 'nl_aw': 'Dutch (Aruba)', 'nl_be': 'Dutch (Belgium)', 'nl_nl': 'Dutch (Netherlands)', 'ps_af': 'Pashto (Afghanistan)', 'pt': 'Portuguese', 'pt_br': 'Portuguese (Brazil)', 'ro': 'Romanian', 'ro_ro': 'Romanian (Romania)', 'rw': 'Kinyarwanda', 'rw_rw': 'Kinyarwanda (Rwanda)', 'sl': 'Slovenian', 'sl_si': 'Slovenian (Slovenia)', 'sr': 'Serbian', 'sr@cyrillic': 'Serbian', 'sr@latn': 'Serbian', 'sr_cs': 'Serbian (Cyrillic, Serbia)', 'sr_cs.iso88592@latn': 'Serbian (Cyrillic, Serbia)', 'sr_cs@latn': 'Serbian (Cyrillic, Serbia)', 'sr_me': 'Serbian (Latin, Montenegro)', 'sr_rs': 'Serbian (Cyrillic, Serbia)', 'sr_rs@latn': 'Serbian (Cyrillic, Serbia)', 'sr_yu': 'Serbian (Cyrillic, Serbia)', 'sr_yu.cp1251@cyrillic': 'Serbian (Cyrillic, Serbia)', 'sr_yu.iso88592': 'Serbian (Cyrillic, Serbia)', 'sr_yu.iso88595': 'Serbian (Cyrillic, Serbia)', 'sr_yu.iso88595@cyrillic': 'Serbian (Cyrillic, Serbia)', 'sr_yu.microsoftcp1251@cyrillic': 'Serbian (Cyrillic, Serbia)', 'sr_yu.utf8': 'Serbian (Cyrillic, Serbia)', 'sr_yu.utf8@cyrillic': 'Serbian (Cyrillic, Serbia)', 'sr_yu@cyrillic': 'Serbian (Cyrillic, Serbia)', 'tr': 'Turkish', 'tr_cy': 'Turkish (Cyprus)', 'tr_tr': 'Turkish (Turkey)', 'vi': 'Vietnamese', 'vi_vn': 'Vietnamese (Vietnam)', 'vi_vn.tcvn': 'Vietnamese (Vietnam)', 'vi_vn.tcvn5712': 'Vietnamese (Vietnam)', 'vi_vn.viscii': 'Vietnamese (Vietnam)', 'vi_vn.viscii111': 'Vietnamese (Vietnam)', 'wo_sn': 'Wolof (Senegal)'}
Try it online!
来源：https://stackoverflow.com/questions/51912028/custom-locale-configuration-for-float-conversion