定义
模块（module）支持从逻辑上组织Python代码，本质就是.py结尾的python文件（e.g.文件名：test.py; 模块名：test），目的是实现某项功能。将其他模块属性附加到你的模块中的操作叫导入（import）。
模块分为三类：标准库、开源模块（open source module)和自定义模块。
包（package）是一个有层次的文件目录结构， 定义了一个由模块和子包组成的python应用程序执行环境。和模块及类一样，也使用句点属性标识来访问他们的元素。使用标准的import和from-import语句导入。
导入模块
导入常用语法
模块导入本质就是一个路径搜索的过程。 即在文件系统“预定义区域”查找你所需要的模块文件。 预定义区域是python搜索路径的集合 - 列表。
# 方法一 import mudule_name #导入整个模块，载入时执行 import module_name as MA # 扩张 as # 方法二 from module_name import name1 # 导入指定模块属性 from module_name import name1 as n1 # 扩张 as #特别注意fe from . import test1 # 相对导入，自当前目录导入test1 from module_name import* # 不建议使用，非良好编程风格，很可能覆盖当前名称空间中现有的名字。
#!usr/bin/envpython #-*-coding:utf-8-*- importsys,os print(sys.path)#返回为列表，包含模块库的路径 x=os.path.dirname(os.path.dirname(os.path.abspath(__file__))) sys.path.append(x)#将指定含有自定义的模块存入模块库路径列表中
import语句和from-import语句的区别
在import语句下，调用模块属性 需要 使用属性/句点属性标识 （如 module_name.logger() 或 os.path.abspath()）的方式。 import语句的本质是将 模块中所有的代码 赋值给 模块名。
而from-import语句是 copy了模块中指定属性的代码并在当前文件下执行。所以，在from-import语句下，不需要用句点属性标识，直接可以调用函数或者类 （logger()）。 在效率上，由于运行方式的不同， from-import语句比import语句的速度更快。
标准库的分类
标准库就其大致用途可分为四类：data persistence and exchange, in-memory data structure, file access, and text process tools。以下是python module of the week 的详细分类
| Categories | Module name | Brief |
| Built-in objects | exceptions | built-in error classes （自动导入） |
| String service | codes | string encoding and decoding |
| difflib | working with text | |
| String IO and cStringIO | work with text buffers using file-like API (read, write. etc.) | |
| re | regular expression | |
| struct | working with Binary Data | |
| textwrap | formatting text paragraphs | |
| Data type | array | sequence of fixed-type data |
| datetime | date/time value manupulation | |
| calendar | work with dates | |
| collections | container data types | |
| heapq | in-place heap sort algorithm | |
| bisect | maintain lists in sorted order | |
| sched | generic event scheduler | |
| Queue | a thread-safe FIFO implementation (comparied with built-in function such as pop() and insert()) | |
| weakref | garbage-collectable references to objects | |
| copy | duplicate objects | |
| pprint | pretty-print data structure | |
| Numeric & mathematical module | decimal | fixed and floating point math |
| fractions | rational numbers | |
| functools | toos for manipultaing functions | |
| itertools | iterator functions for efficient looping | |
| math | mathematical function | |
| operator | functional interface to built-in operators | |
| random | pseudorandom number generator | |
| Internet data handling | base64 | encode binary data into ASCII characters |
| json | JavaScript Object Notation Serializer | |
| mailbox | access and manipulate emial achives | |
| mhlib | work with MH mailboxes | |
| File formats | cvs | comma-separated value files |
| ConfigParser | work with configuration files | |
| robotparser | internet spider access control | |
| Cryptographic services | hashlib | cryptographic hashes and messary digests |
| hmac | cryptographic signature and verification of messages | |
| File and Directory access | os.path | platform-independent manipulation of file names |
| fileinput | process lines from input streams | |
| filecmp | compare files | |
| tempfile | create temporary filesystem resources | |
| glob | filename pattern matching | |
| fnmatch | compare filenames against Unix-style glob partterns | |
| linecache | read text files efficiently | |
| shutil | high-level file opeerations | |
| dircache | cache directory listings | |
| Data compression and archiving | bz2 | bzip2 compression |
| gzip | read and write GNU zip files | |
| tarfile | tar archive access | |
| zipfile | read and write ZIP archive files | |
| zlib | low-level access to GNUzlib compression library | |
| Data persistence | anydbm | access to DBM-style database |
| dbhash | DBM-style API for the BSD database library | |
| dbm | simple database interface | |
| dumbdbm | portable DBM implementation | |
| gdbm | GNU's version of the dbm library | |
| pickle and cPickle | python object serialization | |
| shelve | persistent storage of arbitrary Python objects | |
| whichdb | identify DBM-style database formats | |
| sqlite3 | embedded relational database | |
| Generic operating system service | os | portable access to operating system specific features |
| time | functions for manipulating clock time | |
| getopt | command line option parsing | |
| optparse | command line option parser to replace getopt | |
| argparse | command line option and argument parsing | |
| logging | report status, error, and informational messages | |
| getpass | prompt the user for a password without echoing | |
| platform | access system version information | |
| Optional operating system services | threading | manage concurrent threads |
| mmap | memory-map files | |
| multiprocessing | manage processes like threads | |
| readline | interface to the GNU readline library | |
| rlcompleter | adds tab-completion to the interactive interpreter | |
| Unix-specific services | commands | run external shell commands |
| grp | Unix group database | |
| pipes | Unix shell command pipeline templates | |
| pwd | Unix password database | |
| resource | system resource management | |
| Interprocess communication and networking | asynchat | asynchronous protocol handler |
| asyncore | asynchronous I/O handler | |
| signal | receive notification of asynchronous system events | |
| subprocess | work with additional processes | |
|
Internet protocols and support 网络协议及支持 |
BaseHTTPServer | base classes for implementing web servers |
| cgitb | detailed traceback reports | |
| Cookies | HTTP Cookies | |
| imaplib | IMAP4 client library | |
| SimpleXMLRPCServer | implemens an XML-RPC server | |
| smtpd | Sample SMTP Servers | |
| smtplib | Simple Mail Transfer Protocol client | |
| socket | Network Communication | |
| select | wait for I/O Efficiently | |
| SocketServer | Creating network servers | |
| urllib | simple interface for network reserouce access | |
| urllib2 | Library for opening URLs | |
| urlparse | split URL into component pieces | |
| uuid | universally unique identifiers | |
| webbrowser | Displays web pages | |
| xmlrpclib | client-side liabrary for XML-RPC communication | |
| Structured markup processing tools | xml.etree.ElementTree | XML manipulation API |
|
Internationalization 国际化 |
gettext | Message Catalogs |
| locale | POSIX cultural localization API | |
|
Program frameworks 程序框架 |
cmd | create line-oriented command processes |
| shlex | lexical analysis of shell-style syntaxes | |
|
Development Tools 开发工具 |
doctest | Testing through documentation |
| pydoc | Online help for python modules | |
| unittest | Automated testing framework | |
| pdb | Interative Debugger | |
| Debugging and Profiling | profile, cProfile, and pstats | Performance analysis of Python programs |
| timeit | Time the execution of samll bits of Python code | |
| trace | Follow Python statements as they are executed | |
| Python Runtime Services | abc | Abstract Base Classes |
| atexit | Call functions when a program is closing down | |
| contextlib | context manager utilities | |
| gc | Garbage Collector | |
| inspect | Inspect live objects | |
| site | Site-wide configuration | |
| sys | System-specific Configuration | |
| sysconfig | Interpreter Compile-time Configuration | |
| traceback | Extract, format, and print exceptions and stack traces | |
| warnings | Non-fatal alerts | |
| Python Language Services | compileall | Byte-compile Source Files |
| dis | Python Bytecode Disassembler | |
| pyclbr | Python class browser support | |
| tabnanny | Indentation validator | |
| Importing Modules | imp | Interfact to module import mechanism |
| pkclbr | Package Utilities | |
| zipimport | Load Python code from inside ZIP archives | |
| Miscelaneous | EasyDialogs | Carbon dialogs for Mac OS X |
| plistlib | Manipulate OS X property list files |
Source: python module of the week, Douh Hellmann
Reference
http://www.cnblogs.com/wupeiqi/articles/4963027.html
http://www.cnblogs.com/alex3714/articles/5161349.html
module of the week, 全部标准库模块的释义，非常有用。