[Tutor] Recognizing real numbers

Michael Lewis mjolewis at gmail.com
Wed Feb 22 04:00:40 CET 2012

Hi everyone,

I have some code where I import a file to use a module. That module that I
import takes text and a multiplier, checks for any numbers in that text and
will then multiply those numbers by the given multiplier. The imported
module is below. I am getting the text from a file that I have which starts
out as:

.5 lb. butter
1.75 Cups Graham Cracker Crumbs
2.0 Cups Powder Sugar
1.0 Cups Peanut Butter
2.0 Cups Semi-sweet Chocolate Chips

It seems that the .isdigit() function that I use doesn't recognize the .5
as a number and therefore doesn't multiply it. How can I get my code to
recognize numbers such as .5, 1.75 as numbers?

Imported module:

def MultiplyText(text, multiplier):
    '''Recieve a S & int. For digits in S, multiply by multiplier and
return updated S.'''
    return ' '.join(str(float(num) * multiplier) if num.isdigit() else num
for num in text)

Module doing the importing/opening/reading/creating a new file

import Homework5_1 as multiply

def DoubleDigits(file_name):
    '''Open file/read file/write new file that doubles all int's in the
    read file'''
        read_file = open(file_name)
    except IOError:
        return 'No such file.'
    new_file_name = file_name + '2'
        write_file = open(new_file_name, 'w')
    except IOError:
        return 'No such file to write to.'
    for line in read_file:
        new_line = line.split()
        new_line = ''.join(multiply.MultiplyText(new_line, 2))
        write_file.write(new_line + '\n')

def main():
    DoubleDigits(raw_input('What file do you want to open? '))

if '__name__' == '__main__':
    print main()

Output that is written to my file:

Peanut Butter Bars


.5 lb. butter
1.75 Cups Graham Cracker Crumbs
4.0 Cups Powder Sugar
2.0 Cups Peanut Butter
4.0 Cups Semi-sweet Chocolate Chips

Melt butter. Add graham cracker crumbs,
peanut butter and sugar. Mix well and
pat into sheet pan. Cover with melted
chocolate. Refrigerate until semi-firm,
then cut into squares.

Michael J. Lewis
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