python模块使用

模块 module

• 模块是python组织代码的基本方式
• 一个python脚本可以单独运行，也可以导入到另一个脚本中运行，当脚本被导入运行时，称其为模块（module）
• 所有的.py文件都可以作为一个模块导入
• 模块名与脚本的文件名相同
• 例如写了一个名为hello.py的脚本，则可以在另一个脚本中用import hello语句来导入它

包 package

• python的模块可以按目录组织为包
• 创建一个包的步骤如下：
  1. 创建一个名为包名的目录
  2. 在该目录下创建一个init.py文件
  3. 根据需要，在该目录下存放脚本文件或已编译的扩展及子包
  • import pack.m1,pack.m2,pack.m3

修改环境变量

1. 修改sys.path这个变量

In [1]: import sys

In [2]: sys.path
Out[2]:
['',
 '/usr/bin',
 '/usr/lib64/python27.zip',
 '/usr/lib64/python2.7',
 '/usr/lib64/python2.7/plat-linux2',
 '/usr/lib64/python2.7/lib-tk',
 '/usr/lib64/python2.7/lib-old',
 '/usr/lib64/python2.7/lib-dynload',
 '/usr/lib64/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages/cloud_init-0.7.6-py2.7.egg',
 '/usr/lib/python2.7/site-packages/IPython/extensions',
 '/root/.ipython']

In [3]: sys.path.append('/root/library')

In [4]: sys.path
Out[4]:
['',
 '/usr/bin',
 '/usr/lib64/python27.zip',
 '/usr/lib64/python2.7',
 '/usr/lib64/python2.7/plat-linux2',
 '/usr/lib64/python2.7/lib-tk',
 '/usr/lib64/python2.7/lib-old',
 '/usr/lib64/python2.7/lib-dynload',
 '/usr/lib64/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages/cloud_init-0.7.6-py2.7.egg',
 '/usr/lib/python2.7/site-packages/IPython/extensions',
 '/root/.ipython',
 '/root/library']      # 注意加到末尾

In [5]: '

2. 修改 /root/.bashrc 这个文件

[root@KARL ~]# vim /root/.bashrc #如下所示
[root@KARL ~]# . /root/.bashrc
[root@KARL ~]# echo $PYTHONPATH

/root/library

# .bashrc

# User specific aliases and functions

alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'

# Source global definitions
if [ -f /etc/bashrc ]; then
        . /etc/bashrc
fi

# 末尾添加如下这一句
export PYTHONPATH=/root/library

重新打开一个终端
[root@KARL ~]# . /root/.bashrc
[root@KARL ~]# ipython

In [1]: import sys

In [2]: sys.path
Out[2]:
['',
 '/usr/bin',
 '/root/library',            # 注意加到前面
 '/usr/lib64/python27.zip',
 '/usr/lib64/python2.7',
 '/usr/lib64/python2.7/plat-linux2',
 '/usr/lib64/python2.7/lib-tk',
 '/usr/lib64/python2.7/lib-old',
 '/usr/lib64/python2.7/lib-dynload',
 '/usr/lib64/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages/cloud_init-0.7.6-py2.7.egg',
 '/usr/lib/python2.7/site-packages/IPython/extensions',
 '/root/.ipython']

统计文件的行数、字数、字符数

#!/usr/bin/python
# -*- coding:utf-8 -*-

def wordCount(s):
    chars = len(s)
    words = len(s.split())
    lines = s.count('\n')
    # lines = len(s.split('\n'))                # 这样统计行数会多一行
    print lines, words, chars

with open('/etc/passwd') as fd:
    s = fd.read()
wordCount(s)

[root@KARL ~]# python u1.py
22 31 956
[root@KARL ~]# wc /etc/passwd      # 使用wc统计文件的行数、字数和字符数
 22  31 956 /etc/passwd

[root@KARL ~]# cp u1.py wc.py
[root@KARL ~]# vim u2.py
[root@KARL ~]# cat u2.py
#!/usr/bin/python

import wc
[root@KARL ~]# python u2.py
22 31 956

[root@KARL ~]# vim u2.py
[root@KARL ~]# cat u2.py
#!/usr/bin/python

import wc

s = '''hello workd
python'''
wc.wordCount(s)
[root@KARL ~]# python u2.py
22 31 956
1 3 18

[root@KARL ~]# cat wc.py
#!/usr/bin/python
# -*- coding:utf-8 -*-

def wordCount(s):
    chars = len(s)
    words = len(s.split())
    lines = s.count('\n')
    # lines = len(s.split('\n'))        # 这样统计行数会多一行
    print lines, words, chars

print __name__
'''
with open('/etc/passwd') as fd:
    s = fd.read()
wordCount(s)
'''

[root@KARL ~]# python wc.py
__main__
[root@KARL ~]# python u2.py
wc
1 3 18

 [root@KARL ~]# cat wc.py
#!/usr/bin/python
# -*- coding:utf-8 -*-

def wordCount(s):
    chars = len(s)
    words = len(s.split())
    lines = s.count('\n')
    print lines, words, chars

if __name__ == '__main__':       # 多加1行判断，是的输出符合预期
    with open('/etc/passwd') as fd:
        s = fd.read()
    wordCount(s)
[root@KARL ~]# python wc.py
22 31 956
[root@KARL ~]# python u2.py
1 3 18

包的导入

# 创建空脚本 __init__.py
[root@KARL ~]# mkdir newpack
[root@KARL ~]# cp wc.py newpack/
[root@KARL ~]# touch newpack/__init__.py
[root@KARL ~]# ls newpack/
__init__.py  __init__.pyc  wc.py  wc.pyc

# 1)
In [1]: import newpack.wc

In [2]: wc.wordCount('hell0 \n')
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-2-3146ba553844> in <module>()
----> 1 wc.wordCount('hell0 \n')

NameError: name 'wc' is not defined

In [4]: newpack.wc.wordCount('hello \n')
1 1 7

# 2)
In [1]: from newpack import wc

In [2]: wc.wordCount('abc asd\n')
1 2 8

# 3)
In [1]: from newpack.wc import wordCount

In [2]: wordCount('hello \n')
1 1 7

# 4)
In [1]: from newpack.wc import wordCount as wc

In [2]: wc('hello')
0 1 5