Python 处理EXCEL的CSV文档分列求SUM

import csv
import sys
from optparse import OptionParser

def calculate_profit(day):
    return float(day['Revenue']) - float(day['Cost'])

if __name__ == '__main__':
    parser = OptionParser()
    parser.add_option('-f', '--file', help="CSV Data File")
    opts, args = parser.parse_args()
    if not opts.file:
        parser.error('File name not exist.')
    #Create a dict reader from an open file
        #handle and iterate through rows.
    reader = csv.DictReader(open(opts.file, 'rU'))
    for day in reader:
        print('%10s: %10.2f' % (day['Date'], calculate_profit(day)))

Date,Revenue,Cost
3-May-10,1289.41,889.56
4-May-10,951.89,753.23
5-May-10,2812.23,2541.23
6-May-10,554.25,321.56
7-May-10,1985.65,1536.86
8-May-10,453.36,369.25
9-May-10,2236.87,2003.68
10-May-10,1825.63,1658.96
11-May-10,951.89,852.36