Python Learning note 12-module usage

Python Learning note 12-module usage

Module Os,sys

What is a module?

Module Os,sys

Modules are a basic way for Python to organize your code

A python script can be run on its own, or it can be imported into another script, imported with an import Hello statement, and not joined. PY

What is a python package?

Python modules can be organized into packages according to directory

Steps to create a package:

Create a directory with the name of the package name

Create a __init__.py file under Change directory

If necessary, place script files or compiled extensions and sub-packages in this directory

Import pack.m1,pack.m2,pack.m3

View Python

Sys.path

Export Pythonpat

in [311]: import sysin [312]: sys.pathout[312]: [',  '/usr/local/bin ',   '/usr/local/lib/python27.zip ',  '/usr/local/lib/python2.7 ',  '/usr/local/lib/python2.7/ Plat-linux2 ',  '/usr/local/lib/python2.7/lib-tk ',  '/usr/local/lib/python2.7/lib-old ',  '/usr/ Local/lib/python2.7/lib-dynload ',  '/usr/local/lib/python2.7/site-packages ',  '/usr/local/lib/ Python2.7/site-packages/ipython/extensions ',  '/root/.ipython ']in [313]: import stringin  [314]: import  T---------------------------------------------------------------------------importerror                                 Traceback  (most recent call  Last) <ipython-input-314-c2d7a4e4fb09> in <module> ()----> 1 import  timporterror: no module named t# cannot find this module [[email protected] ~]# ls /usr/local/lib/python2.7/ string.py/usr/local/lib/python2.7/string.py[[email protected] ~]# ls /usr/local/lib/ python2.7/os.py/usr/local/lib/python2.7/os.py

Customize the path of Python, some of the tools you have developed can be placed in this directory

Method One: Through Sys.path.append ('/root/library ')

[Email protected] ~]# Mkdir/root/libraryin [315]: Sys.path.append ('/root/library ') in [[]: sys.pathout[316]: [', '/ Usr/local/bin ', '/usr/local/lib/python27.zip ', '/usr/local/lib/python2.7 ', '/usr/local/lib/python2.7/plat-linux2 ' , '/usr/local/lib/python2.7/lib-tk ', '/usr/local/lib/python2.7/lib-old ', '/usr/local/lib/python2.7/lib-dynload ', ' /usr/local/lib/python2.7/site-packages ', '/usr/local/lib/python2.7/site-packages/ipython/extensions ', '/root/. Ipython ', '/root/library ']

Method Two, modify the/ROOT/.BASHRC

[Email protected] ~]# VIM/ROOT/.BASHRC

Add a line: Export pythonpath=/root/library

[Email protected] ~]#. /ROOT/.BASHRC [[email protected] ~]# echo $PYTHONPATH/root/library[[email protected] ~]# Ipythonin [2]: Import Sysin [3]: SYS.PATHOUT[3]: [' ', '/usr/local/bin ', '/root/library ', '/usr/local/lib/python27.zip ', '/usr/local/lib/python2.7 ', ' /usr/local/lib/python2.7/plat-linux2 ', '/usr/local/lib/python2.7/lib-tk ', '/usr/local/lib/python2.7/lib-old ', '/ Usr/local/lib/python2.7/lib-dynload ', '/usr/local/lib/python2.7/site-packages ', '/usr/local/lib/python2.7/ Site-packages/ipython/extensions ',

Instance:

In [2]: with open ('/etc/hosts ')  as fd:   ...:      s = fd.read () in [4]: s.count (' \ n ')   #统计行数, using \ n line break as the standard for segmentation out[4]: 19 [[ Email protected] ~]# vim wordcount.py #!/usr/bin/pythondef wordcount (s):     chars = len (s)            #统计字符数     words = len (S.split ())    #统计单词数量,     lines  = s.count (' \ n ')     #统计行数, the number of occurrences is the standard, cannot use Lines=len (s.splid (' \ n ')), so that the final end of \ n will count a row of None     print lines,words,charss = open ('/etc/passwd '). Read () wordCount (s) [[ Email protected] ~]# python wordcount.py 42 71 2051[[email protected]  ~]# wc /etc/passwd42   71 2051 /etc/passwd[[email protected]  ~]# vim wordcount.py [[email protected] ~]# vim test.py   #默认是找的当前目录下的 #!/usr/bin/ pythonimport wordcount[[email protected] ~]# python test.py 42 71 2051 [[email protected] ~]# ll  # When wordcount.py is used as a module, it generates a compiled file Wordcount.pyc, and when referenced again, the higher the overall dosage  36drwxr-xr-x  2 root root  4096 9 Month    8 04:30 library-rw-r--r--  1 root root    38 9 Month    8 04:59 test.py-rw-r--r--  1 root root   182 9 Month    8 04:54 wordcount.py-rw-r--r--  1 root  Root  424 9 Month    8 05:00 WORDCOUNT.PYC

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Python Learning note 12-module usage