Python CSV模块处理文件读写

下面是一个简单的csv文件

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

使用csv模块处理

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

可以使用for-in循环逐条访问reader中的list类型元素，使用csv模块非常智能，可以处理元素内含逗号的复杂csv文件。reader.line_num记录着目前读到第几行。

处理换行符 

有一点要注意的是，如果用excel文件另存为csv文件，读行尾符号可能会遇到问题

Error: new-line character seen in unquoted field - do you need to open the file in universal-newline mode?

这时候下面这种方式打开文件就没有问题啦

csv.reader(open(filename,"rU")) 

改变分隔符

创建一csv.excel的子类，并修改分隔符为”;”

# 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

如果仅仅仅是改变一两个参数，则可以直接在reader参数中设置，如下：

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

将数据存为CSV格式

通过csv.writer来生成一csv文件。

# 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)
# writer = csv.writer(open("out.csv","w"))
 
for item in data:
    writer.writerow(item)

参考:

http://www.pythonclub.org/python-files/csv

http://stackoverflow.com/questions/2930673/python-and-csv-help