A simple python script to reduce or reformat a csv file, producing a csv with a specific sub-set of columns, stripping out any undesired characters from the individual row values

reformat_csv.py

'''

A simple python script to reduce or reformat a csv file, producing a
csv with a specific sub-set of columns, stripping out any undesired
characters from the individual row values.

'''


import csv
import re
import sys


# Define the column headers from the original csv to be preserve in the reformatted csv
headers = [
    'Account Name/Number',
    'Symbol',
    'Description',
    'Quantity',
    'Last Price',
    'Current Value',
    'Total Gain/Loss Dollar',
    'Total Gain/Loss Percent',
    'Cost Basis Per Share',
    'Cost Basis Total'
]


# Define a regex expression for letters and characters to remove from individual cell values
unneeded = re.compile(r'(\+|\$|%|--|n/a)')

if __name__ == "__main__":
    """Create a command-line main() entry point"""

    if len(sys.argv) < 2:
        # Define the usage
        print(sys.argv[0], '[input csv file] [output csv file]')
    else:
        with open(sys.argv[1], 'r') as csv_input:
            with open(sys.argv[2], 'w') as csv_output:
                writer = csv.DictWriter(csv_output, fieldnames=headers)
                for row in csv.DictReader(csv_input):
                    # ignore any row which does not contain all the required columns
                    if not None in [row[x] for x in headers]:
                        writer.writerow({x: unneeded.sub('', row[x]) for x in headers})