python - 在python中读取csv文件两次

Question

这是我的 Python 代码:

import csv

# Reading
ordersFile = open('orders.csv', 'rb')
ordersR = csv.reader(ordersFile, delimiter=',')

# Find order employeeID=5, shipCountry="Brazil"
print "Find order employeeID=5, shipCountry=\"Brazil\""
for order in ordersR:
    if order[2] == '5' and order[13] == 'Brazil':
        print order
# Find order employeeID=5
print "Find order employeeID=5"
for order in ordersR:
    if order[2] == '5':
        print order
ordersFile.close()

我可以打印“# Find order employeeID=5, shipCountry="Brazil"”的内容，但对于#Find order employeeID=5 我什么也得不到。我在考虑如何多次读取(选择)同一个 csv 文件中的行。

Answer 1

您只是直接阅读 CSV 文件，但如果您想分多次处理数据，则应将内容读入变量。这样您就不必在每次需要处理文件时都重新读取文件。

import csv

# Read order rows into our list
# Here I use a context manager so that the file is automatically
# closed upon exit
with open('orders.csv') as orders_file:
    reader = csv.reader(orders_file, delimiter=',')
    orders = list(reader)

# Find order employeeID=5, shipCountry="Brazil"
print "Find order employeeID=5, shipCountry=\"Brazil\""
for order in orders:
    if order[2] == '5' and order[13] == 'Brazil':
        print order

# Find order employeeID=5
print "Find order employeeID=5"
for order in orders:
    if order[2] == '5':
        print order

如果您的 CSV 文件太大而无法放入内存(或者出于某种原因您不想将其全部读入内存)，那么您将需要一种不同的方法。如果您需要，请发表评论。