Parse currency into numbers in Python
Below is a general currency parser that doesn't rely on the babel library.
import numpy as np
import re
def currency_parser(cur_str):
# Remove any non-numerical characters
# except for ',' '.' or '-' (e.g. EUR)
cur_str = re.sub("[^-0-9.,]", '', cur_str)
# Remove any 000s separators (either , or .)
cur_str = re.sub("[.,]", '', cur_str[:-3]) + cur_str[-3:]
if '.' in list(cur_str[-3:]):
num = float(cur_str)
elif ',' in list(cur_str[-3:]):
num = float(cur_str.replace(',', '.'))
else:
num = float(cur_str)
return np.round(num, 2)
Here is a pytest script that tests the function:
import numpy as np
import pytest
import re
def currency_parser(cur_str):
# Remove any non-numerical characters
# except for ',' '.' or '-' (e.g. EUR)
cur_str = re.sub("[^-0-9.,]", '', cur_str)
# Remove any 000s separators (either , or .)
cur_str = re.sub("[.,]", '', cur_str[:-3]) + cur_str[-3:]
if '.' in list(cur_str[-3:]):
num = float(cur_str)
elif ',' in list(cur_str[-3:]):
num = float(cur_str.replace(',', '.'))
else:
num = float(cur_str)
return np.round(num, 2)
@pytest.mark.parametrize('currency_str, expected', [
(
'.3', 0.30
),
(
'1', 1.00
),
(
'1.3', 1.30
),
(
'43,324', 43324.00
),
(
'3,424', 3424.00
),
(
'-0.00', 0.00
),
(
'EUR433,432.53', 433432.53
),
(
'25.675,26 EUR', 25675.26
),
(
'2.447,93 EUR', 2447.93
),
(
'-540,89EUR', -540.89
),
(
'67.6 EUR', 67.60
),
(
'30.998,63 CHF', 30998.63
),
(
'0,00 CHF', 0.00
),
(
'159.750,00 DKK', 159750.00
),
(
'£ 2.237,85', 2237.85
),
(
'£ 2,237.85', 2237.85
),
(
'-1.876,85 SEK', -1876.85
),
(
'59294325.3', 59294325.30
),
(
'8,53 NOK', 8.53
),
(
'0,09 NOK', 0.09
),
(
'-.9 CZK', -0.9
),
(
'35.255,40 PLN', 35255.40
),
(
'-PLN123.456,78', -123456.78
),
(
'US$123.456,79', 123456.79
),
(
'-PLN123.456,78', -123456.78
),
(
'PLN123.456,79', 123456.79
),
(
'IDR123.457', 123457
),
(
'JP¥123.457', 123457
),
(
'-JP\xc2\xa5123.457', -123457
),
(
'CN\xc2\xa5123.456,79', 123456.79
),
(
'-CN\xc2\xa5123.456,78', -123456.78
),
])
def test_currency_parse(currency_str, expected):
assert currency_parser(currency_str) == expected
Using babel
The babel documentation notes that the number parsing is not fully implemented yes but they have done a lot of work to get currency info into the library. You can use get_currency_name() and get_currency_symbol() to get currency details, and also all other get_... functions to get the normal number details (decimal point, minus sign, etc.).
Using that information you can exclude from a currency string the currency details (name, sign) and groupings (e.g. , in the US). Then you change the decimal details into the ones used by the C locale (- for minus, and . for the decimal point).
This results in this code (i added an object to keep some of the data, which may come handy in further processing):
import re, os
from babel import numbers as n
from babel.core import default_locale
class AmountInfo(object):
def __init__(self, name, symbol, value):
self.name = name
self.symbol = symbol
self.value = value
def parse_currency(value, cur):
decp = n.get_decimal_symbol()
plus = n.get_plus_sign_symbol()
minus = n.get_minus_sign_symbol()
group = n.get_group_symbol()
name = n.get_currency_name(cur)
symbol = n.get_currency_symbol(cur)
remove = [plus, name, symbol, group]
for token in remove:
# remove the pieces of information that shall be obvious
value = re.sub(re.escape(token), '', value)
# change the minus sign to a LOCALE=C minus
value = re.sub(re.escape(minus), '-', value)
# and change the decimal mark to a LOCALE=C decimal point
value = re.sub(re.escape(decp), '.', value)
# just in case remove extraneous spaces
value = re.sub('\s+', '', value)
return AmountInfo(name, symbol, value)
#cur_loc = os.environ['LC_ALL']
cur_loc = default_locale()
print('locale:', cur_loc)
test = [ (n.format_currency(123456.789, 'USD', locale=cur_loc), 'USD')
, (n.format_currency(-123456.78, 'PLN', locale=cur_loc), 'PLN')
, (n.format_currency(123456.789, 'PLN', locale=cur_loc), 'PLN')
, (n.format_currency(123456.789, 'IDR', locale=cur_loc), 'IDR')
, (n.format_currency(123456.789, 'JPY', locale=cur_loc), 'JPY')
, (n.format_currency(-123456.78, 'JPY', locale=cur_loc), 'JPY')
, (n.format_currency(123456.789, 'CNY', locale=cur_loc), 'CNY')
, (n.format_currency(-123456.78, 'CNY', locale=cur_loc), 'CNY')
]
for v,c in test:
print('As currency :', c, ':', v.encode('utf-8'))
info = parse_currency(v, c)
print('As value :', c, ':', info.value)
print('Extra info :', info.name.encode('utf-8')
, info.symbol.encode('utf-8'))
The output looks promising (in US locale):
$ export LC_ALL=en_US
$ ./cur.py
locale: en_US
As currency : USD : b'$123,456.79'
As value : USD : 123456.79
Extra info : b'US Dollar' b'$'
As currency : PLN : b'-z\xc5\x82123,456.78'
As value : PLN : -123456.78
Extra info : b'Polish Zloty' b'z\xc5\x82'
As currency : PLN : b'z\xc5\x82123,456.79'
As value : PLN : 123456.79
Extra info : b'Polish Zloty' b'z\xc5\x82'
As currency : IDR : b'Rp123,457'
As value : IDR : 123457
Extra info : b'Indonesian Rupiah' b'Rp'
As currency : JPY : b'\xc2\xa5123,457'
As value : JPY : 123457
Extra info : b'Japanese Yen' b'\xc2\xa5'
As currency : JPY : b'-\xc2\xa5123,457'
As value : JPY : -123457
Extra info : b'Japanese Yen' b'\xc2\xa5'
As currency : CNY : b'CN\xc2\xa5123,456.79'
As value : CNY : 123456.79
Extra info : b'Chinese Yuan' b'CN\xc2\xa5'
As currency : CNY : b'-CN\xc2\xa5123,456.78'
As value : CNY : -123456.78
Extra info : b'Chinese Yuan' b'CN\xc2\xa5'
And it still works in different locales (Brazil is notable for using the comma as a decimal mark):
$ export LC_ALL=pt_BR
$ ./cur.py
locale: pt_BR
As currency : USD : b'US$123.456,79'
As value : USD : 123456.79
Extra info : b'D\xc3\xb3lar americano' b'US$'
As currency : PLN : b'-PLN123.456,78'
As value : PLN : -123456.78
Extra info : b'Zloti polon\xc3\xaas' b'PLN'
As currency : PLN : b'PLN123.456,79'
As value : PLN : 123456.79
Extra info : b'Zloti polon\xc3\xaas' b'PLN'
As currency : IDR : b'IDR123.457'
As value : IDR : 123457
Extra info : b'Rupia indon\xc3\xa9sia' b'IDR'
As currency : JPY : b'JP\xc2\xa5123.457'
As value : JPY : 123457
Extra info : b'Iene japon\xc3\xaas' b'JP\xc2\xa5'
As currency : JPY : b'-JP\xc2\xa5123.457'
As value : JPY : -123457
Extra info : b'Iene japon\xc3\xaas' b'JP\xc2\xa5'
As currency : CNY : b'CN\xc2\xa5123.456,79'
As value : CNY : 123456.79
Extra info : b'Yuan chin\xc3\xaas' b'CN\xc2\xa5'
As currency : CNY : b'-CN\xc2\xa5123.456,78'
As value : CNY : -123456.78
Extra info : b'Yuan chin\xc3\xaas' b'CN\xc2\xa5'
It is worth to point out that babel has some encoding problems. That is because the locale files (in locale-data) do use different encoding themselves. If you're working with currencies you're familiar with that should not be a problem. But if you try unfamiliar currencies you might run into problems (i just learned that Poland uses iso-8859-2, not iso-8859-1).