Python程序中用csv模块来操作csv文件的基本使用教程

Title,Release Date,Director
And Now For Something Completely Different,1971,Ian MacNaughton
Monty Python And The Holy Grail,1975,Terry Gilliam and Terry Jones
Monty Python's Life Of Brian,1979,Terry Jones
Monty Python Live At The Hollywood Bowl,1982,Terry Hughes
Monty Python's The Meaning Of Life,1983,Terry Jones

for line in open("samples/sample.csv"):
  title, year, director = line.split(",")
  print year, title

import csv
reader = csv.reader(open("samples/sample.csv"))
for title, year, director in reader:
  print year, title

# File: csv-example-2.py
import csv
class SKV(csv.excel):
  # like excel, but uses semicolons
  delimiter = ";"
 
csv.register_dialect("SKV", SKV)
reader = csv.reader(open("samples/sample.skv"), "SKV")
for title, year, director in reader:
  print year, title

# File: csv-example-3.py
 
import csv
 
reader = csv.reader(open("samples/sample.skv"), delimiter=";")
 
for title, year, director in reader:
  print year, title

# File: csv-example-4.py
 
import csv
import sys
 
data = [
  ("And Now For Something Completely Different", 1971, "Ian MacNaughton"),
  ("Monty Python And The Holy Grail", 1975, "Terry Gilliam, Terry Jones"),
  ("Monty Python's Life Of Brian", 1979, "Terry Jones"),
  ("Monty Python Live At The Hollywood Bowl", 1982, "Terry Hughes"),
  ("Monty Python's The Meaning Of Life", 1983, "Terry Jones")
]
 
writer = csv.writer(sys.stdout)
 
for item in data:
  writer.writerow(item)

import csv


# dialect是访问csv文件时需要指定的参数之一，用来确定csv文件的数据格式
# 下面这个函数列举系统支持的dialect有哪些，默认值是'excel'，用户也可
# 以从Dialect派生一个类，使用该类的实例作为dialect参数。
print csv.list_dialects()


def test_writer():
  # csv文件必须以二进制方式open
  with open('eggs.csv', 'wb') as csvfile:
    spamwriter = csv.writer(csvfile)
    spamwriter.writerow(['Spam'] * 5 + ['Baked Beans'])
    spamwriter.writerow(['Spam', 'Lovely Spam', 'Wonderful Spam'])


def test_reader():
  with open('eggs.csv', 'rb') as csvfile:
    spamreader = csv.reader(csvfile)
    for row in spamreader:
      print row


# sniffer 用来推断csv文件的格式，不是很准确
def test_sniffer():
  with open('eggs.csv', 'wb') as csvfile:
    spamwriter = csv.writer(csvfile, delimiter=' ')

    spamwriter.writerow(['Spam'] * 2 + ['Baked Beans'])
    spamwriter.writerow(['Spam', 'Lovely Spam', 'Wonderful Spam'])

  # 通常你需要指定与写入者相同的文件格式才能正确的读取数据
  with open('eggs.csv', 'rb') as csvfile:
    spamreader = csv.reader(csvfile, delimiter=' ')
    for row in spamreader:
      print ', '.join(row)

  # 如果不知道文件格式，sniffer就可以派上用场了
  with open('eggs.csv', 'rb') as csvfile:
    # 用sniffer推断文件格式，从而得到dialect
    dialect = csv.Sniffer().sniff(csvfile.read(1024))
    print dialect.delimiter, dialect.quotechar

    # 文件重新移动到头部
    csvfile.seek(0)

    # 用推断出来的dialect创建reader
    reader = csv.reader(csvfile, dialect)

    for row in reader:
      print ', '.join(row)