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
['\xe5\xa7\x93\xe5\x90\x8d', '\xe5\xb9\xb4\xe9\xbe\x84', '\xe7\x94\xb5\xe8\xaf\x9d']
['\xe5\xb0\x8f\xe6\xb2\xb3', '25', '1234567']
['\xe5\xb0\x8f\xe8\x8a\xb3', '18', '789456']
打印发行日期及标题，逐行处理：
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for
line
in
open
(
"samples/sample.csv"
):
title, year, director
=
line.split(
","
)
print
year, title
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使用csv模块处理：
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import
csv
reader
=
csv.reader(
open
(
"samples/sample.csv"
))
for
title, year, director
in
reader:
print
year, title
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改变分隔符
创建一csv.excel的子类，并修改分隔符为”;”
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# 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
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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：
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# File: csv-example-3.py
import
csv
reader
=
csv.reader(
open
(
"samples/sample.skv"
), delimiter
=
";"
)
for
title, year, director
in
reader:
print
year, title
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将数据存为CSV格式
通过csv.writer来生成一csv文件。
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# 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)
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