Convert a number enclosed in parentheses (string) to a negative integer (or float) using Python?

Question

In Python, what is the simplest way to convert a number enclosed in parentheses (string) to a negative integer (or float)?

For example, '(4,301)' to -4301, as commonly encountered in accounting applications.

Answer 1

The simplest way is:

my_str = "(4,301)"
num = -int(my_str.translate(None,"(),"))

Answer 2

Since you are reading from a system that put in thousands separators, it's worth mentioning that we are not using them the same way all around the world, which is why you should consider using a locale system. Consider:

import locale
locale.setlocale( locale.LC_ALL, 'en_US.UTF-8' )
my_str = "(4,301)"
result = -locale.atoi(my_str.translate(None,"()"))

Answer 3

Assuming just removing the , is safe enough, and you may wish to apply the same function to values that may contain negative numbers or not, then:

import re
print float(re.sub(r'^\((.*?)\)$', r'-\1', a).replace(',',''))

You could then couple that with using locale as other answers have shown, eg:

import locale, re

locale.setlocale(locale.LC_ALL, 'en_GB.UTF-8')
print locale.atof(re.sub('^\((.*?)\)$', r'-\1', a))

Answer 4

For Python 3.6, and also handles '-' as 0, and strips excess empty spaces:

def clean_num(num_string):
    bad_chars = '(),-'
    translator = str.maketrans('', '', bad_chars)
    clean_digits = num_string.translate(translator).strip()

    if clean_digits == '':
        return 0
    elif '(' in num_string:
        return -float(clean_digits)
    else:
        return float(clean_digits) 

Answer 5

Presumably you want to handle positive numbers as well as negative, which is missing from many of the answers thus far. I'm going to add a bit to the answer from mogul .

import locale
locale.setlocale( locale.LC_ALL, '')
my_str = '( 4,301 )'
positive = my_str.translate(None, '()')
result = locale.atoi(positive) if positive == my_str else -locale.atoi(positive)

Answer 6

This code could be a little bit longer, but straight forward and easy to maintain

from pyparsing import Word, nums, OneOrMore

integer = Word(nums)

text = "blah blah (4,301) blah blah " 

parser = OneOrMore(integer)

iterator = parser.scanString( text )

try:
    while True:
        part1 =  iterator.next()
        part2 =  iterator.next()
except:
    x =  part1[0][0][0] + '.' +part2[0][0][0]
    print -float(x)

Produces : -4.301

Answer 7

For localized numbers, I use this:

def clean_number(text):
    import locale
    locale.setlocale(locale.LC_NUMERIC, "Portuguese_Brazil.1252")
    tbl = str.maketrans('(', '-', 'R$ )')
    return locale.atof(text.translate(tbl))

Works with Python 3.8. The first parenthesis is replaced with the minus sign, the second is removed. Also removes spaces and the monetary sign.