Python 的 CSV模块的使用方法,包括,reader, writer, DictReader, DictWriter.register_dialect
一直非常喜欢python的csv模块,简单易用,经常在项目中使用,现在举几个例子说明一下。
reader(csvfile[, dialect='excel'][, fmtparam])
参数表:
csvfile
需要是支持迭代(Iterator)的对象,并且每次调用next方法的返回值是字符串(string),通常的文件(file)对象,或者列表(list)对象都是适用的,如果是文件对象,打开是需要加"b"标志参数。
dialect
编码风格,默认为excel方式,也就是逗号(,)分隔,另外csv模块也支持excel-tab风格,也就是制表符(tab)分隔。其它的方式需要自己定义,然后可以调用register_dialect方法来注册,以及list_dialects方法来查询已注册的所有编码风格列表。
fmtparam
格式化参数,用来覆盖之前dialect对象指定的编码风格。
例子:
import csv reader = (file('your.csv', 'rb')) for line in reader: print line
writer(csvfile[, dialect='excel'][, fmtparam])
参数表(略: 同reader, 见上)
例子:
import csv writer = (file('your.csv', 'wb')) (['Column1', 'Column2', 'Column3']) lines = [range(3) for i in range(5)] for line in lines: writer.writerow(line)
1. 写入并生成csv文件
代码:
# coding: utf-8
import csv
csvfile = file('csv_test.csv', 'wb')
writer = csv.writer(csvfile)
writer.writerow(['姓名', '年龄', '电话'])
data = [
('小河', '25', '1234567'),
('小芳', '18', '789456')
]
writer.writerows(data)
csvfile.close()
-
wb中的w表示写入模式,b是文件模式
-
写入一行用writerow
-
多行用writerows
2. 读取csv文件
代码:
# coding: utf-8
import csv
csvfile = file('csv_test.csv', 'rb')
reader = csv.reader(csvfile)
for line in reader:
print line
csvfile.close()
运行结果:
root@he-desktop:~/python/example# python read_csv.py
['xe5xa7x93xe5x90x8d', 'xe5xb9xb4xe9xbex84', 'xe7x94xb5xe8xafx9d']
['xe5xb0x8fxe6xb2xb3', '25', '1234567']
['xe5xb0x8fxe8x8axb3', '18', '789456']
打印发行日期及标题,逐行处理:
1
2
3
|
for line in open ( "samples/sample.csv" ): title, year, director = line.split( "," ) print year, title |
使用csv模块处理:
1
2
3
4
|
import csv reader = csv.reader( open ( "samples/sample.csv" )) for title, year, director in reader: print year, title |
改变分隔符
创建一csv.excel的子类,并修改分隔符为”;”
1
2
3
4
5
6
7
8
9
10
|
# 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:
1
2
3
4
5
6
7
8
|
# 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。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
|
# 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) |