如何使用Python读写CSV文件？

Question

我有一个example.csv包含内容的文件

1,"A towel,",1.0
42," it says, ",2.0
1337,is about the most ,-1
0,massively useful thing ,123
-2,an interstellar hitchhiker can have.,3

如何example.csv使用Python 阅读？

同样，如果我有

data = [(1, "A towel,", 1.0),
        (42, " it says, ", 2.0),
        (1337, "is about the most ", -1),
        (0, "massively useful thing ", 123),
        (-2, "an interstellar hitchhiker can have.", 3)]

如何data使用Python 写入CSV文件？

Answer 1

以下是一些最小的完整示例，这些示例如何读取CSV文件以及如何使用Python编写CSV文件。

Python 2 + 3：读取CSV文件

Python

# -*- coding: utf-8 -*-

import csv
import sys

# Define data
data = [(1, "A towel,", 1.0),
        (42, " it says, ", 2.0),
        (1337, "is about the most ", -1),
        (0, "massively useful thing ", 123),
        (-2, "an interstellar hitchhiker can have.", 3)]

# Write CSV file
kwargs = {'newline': ''}
mode = 'w'
if sys.version_info < (3, 0):
    kwargs.pop('newline', None)
    mode = 'wb'

with open('test.csv', mode, **kwargs) as fp:
    writer = csv.writer(fp, delimiter=',')
    # writer.writerow(["your", "header", "foo"])  # write header
    writer.writerows(data)

# Read CSV file
kwargs = {'newline': ''}
mode = 'r'
if sys.version_info < (3, 0):
    kwargs.pop('newline', None)
    mode = 'rb'
with open('test.csv', mode, **kwargs) as fp:
    reader = csv.reader(fp, delimiter=',', quotechar='"')
    # next(reader, None)  # skip the headers
    data_read = [row for row in reader]

print(data_read)

之后，的内容data_read是

[['1', 'A towel,', '1.0'],
 ['42', ' it says, ', '2.0'],
 ['1337', 'is about the most ', '-1'],
 ['0', 'massively useful thing ', '123'],
 ['-2', 'an interstellar hitchhiker can have.', '3']]

Unicode和Python 2.X

如果要编写Unicode，则必须安装unicodecsv。千万不能用打开文件codecs.open，而只是用open。用写

import unicodecsv as csv
# Write CSV file
with open('test.csv', 'w', newline='') as fp:
    writer = csv.writer(fp, encoding='utf-8')
    # writer.writerow(["your", "header", "foo"])  # write header
    writer.writerows(data)