Python Data Structure 简明教程

Python - DS Environment

Python 可用于各种平台，包括 Linux 和 Mac OS X。让我们了解如何设置我们的 Python 环境。

Python is available on a wide variety of platforms including Linux and Mac OS X. Let’s understand how to set up our Python environment.

Local Environment Setup

打开一个终端窗口并输入“python”以找出它是否已经安装，以及安装的是哪个版本。

Open a terminal window and type "python" to find out if it is already installed and which version is installed.

  1. Unix (Solaris, Linux, FreeBSD, AIX, HP/UX, SunOS, IRIX, etc.)

  2. Win 9x/NT/2000

  3. Macintosh (Intel, PPC, 68K)

  4. OS/2

  5. DOS (multiple versions)

  6. PalmOS

  7. Nokia mobile phones

  8. Windows CE

  9. Acorn/RISC OS

  10. BeOS

  11. Amiga

  12. VMS/OpenVMS

  13. QNX

  14. VxWorks

  15. Psion

  16. Python has also been ported to the Java and .NET virtual machines

Getting Python

最新的源代码、二进制文件、文档、新闻等可在 Python 的官方网站上找到 www.python.org

The most up-to-date and current source code, binaries, documentation, news, etc., is available on the official website of Python www.python.org

您可以从此处提供的网站下载 Python 文档， www.python.org/doc 。文档提供 HTML、PDF 和 PostScript 格式。

You can download Python documentation from this website given herewith,www.python.org/doc. The documentation is available in HTML, PDF, and PostScript formats.

Installing Python

Python 发行版可用于各种平台。你只需下载适用于你的平台的二进制代码并安装 Python。

Python distribution is available for a wide variety of platforms. You need to download only the binary code applicable for your platform and install Python.

如果你的平台没有二进制代码，你需要 C 编译器来手动编译源代码。编译源代码在安装中所需特性的选择方面提供了更大的灵活性。

If the binary code for your platform is not available, you need a C compiler to compile the source code manually. Compiling the source code offers more flexibility in terms of choice of features that you require in your installation.

以下是对在各种平台上安装 Python 的快速概述 −

Here is a quick overview of installing Python on various platforms −

Unix and Linux Installation

以下是在 Unix/Linux 计算机上安装 Python 的简单步骤。

Here are the simple steps to install Python on Unix/Linux machine.

  1. Open a Web browser and go to www.python.org/downloads.

  2. Follow the link to download zipped source code available for Unix/Linux.

  3. Download and extract files.

  4. Editing the Modules/Setup file if you want to customize some options.

  5. run ./configure script

  6. make

  7. make install

这将在标准位置 /usr/local/bin 安装 Python，并将其库安装在 /usr/local/lib/pythonXX ，其中 XX 是 Python 的版本。

This installs Python at standard location /usr/local/bin and its libraries at /usr/local/lib/pythonXX where XX is the version of Python.

Windows Installation

以下是如何在 Windows 机器上安装 Python：

Here are the steps to install Python on Windows machine.

  1. Open a Web browser and go to www.python.org/downloads.

  2. Follow the link for the Windows installer python-XYZ.msi file where XYZ is the version you need to install.

  3. To use this installer python-XYZ.msi, the Windows system must support Microsoft Installer 2.0. Save the installer file to your local machine and then run it to find out if your machine supports MSI.

  4. Run the downloaded file. This brings up the Python install wizard, which is really easy to use. Just accept the default settings, wait until the install is finished, and you are done.

Macintosh Installation

最新款的 Mac 电脑都内置了 Python，但可能会有好几年的时差。请参见 www.python.org/download/mac/ 以获取有关同时与支持 Mac 开发的额外工具一起获取当前版本的说明。对于在 Mac OS X 10.3（2003 年发布）之前的较旧的 Mac 操作系统，MacPython 可用。

Recent Macs come with Python installed, but it may be several years out of date. See www.python.org/download/mac/ for instructions on getting the current version along with extra tools to support development on the Mac. For older Mac OS’s before Mac OS X 10.3 (released in 2003), MacPython is available.

由 Jack Jansen 维护，您可以在他的网站上完全访问完整的文档 − 链接：http://www.cwi.nl/ jack/macpython.html[http://www.cwi.nl/ jack/macpython.html]。您可以找到 Mac OS 安装的完整安装详细信息。

Jack Jansen maintains it and you can have full access to the entire documentation at his website − http://www.cwi.nl/jack/macpython.html. You can find complete installation details for Mac OS installation.

Setting up PATH

程序和其他可执行文件可以位于许多目录中，因此操作系统会提供一个搜索路径，其中列出了操作系统搜索可执行文件的目录。

Programs and other executable files can be in many directories, so operating systems provide a search path that lists the directories that the OS searches for executables.

路径存储在环境变量中，该变量是由操作系统维护的一个已命名字符串。此变量包含可供命令 shell 和其他程序使用的信息。

The path is stored in an environment variable, which is a named string maintained by the operating system. This variable contains information available to the command shell and other programs.

path 变量在 Unix 中被命名为 PATH，在 Windows 中被命名为 Path（Unix 区分大小写；Windows 不区分大小写）。

The path variable is named as PATH in Unix or Path in Windows (Unix is case sensitive; Windows is not).

在 Mac OS 中，安装程序会处理路径详细信息。要从任何特定目录调用 Python 解释器，您必须将 Python 目录添加到您的路径中。

In Mac OS, the installer handles the path details. To invoke the Python interpreter from any particular directory, you must add the Python directory to your path.

Setting path at Unix/Linux

要在 Unix 中为特定会话将 Python 目录添加到路径中 −

To add the Python directory to the path for a particular session in Unix −

  1. In the csh shell − type setenv PATH "$PATH:/usr/local/bin/python" and press Enter.

  2. In the bash shell (Linux) − type export ATH="$PATH:/usr/local/bin/python" and press Enter.

  3. In the sh or ksh shell − type PATH="$PATH:/usr/local/bin/python" and press Enter.

  4. Note − /usr/local/bin/python is the path of the Python directory

Setting path at Windows

要在Windows特定会话的路径中添加Python目录：

To add the Python directory to the path for a particular session in Windows −

  1. At the command prompt − type path %path%;C:\Python and press Enter.

  2. Note − C:\Python is the path of the Python directory

Python Environment Variables

以下是Python可以识别的重要环境变量：

Here are important environment variables, which can be recognized by Python −

Sr.No.

Variable & Description

1

PYTHONPATH It has a role similar to PATH. This variable tells the Python interpreter where to locate the module files imported into a program. It should include the Python source library directory and the directories containing Python source code. PYTHONPATH is sometimes preset by the Python installer.

2

PYTHONSTARTUP It contains the path of an initialization file containing Python source code. It is executed every time you start the interpreter. It is named as .pythonrc.py in Unix and it contains commands that load utilities or modify PYTHONPATH.

3

PYTHONCASEOK It is used in Windows to instruct Python to find the first case-insensitive match in an import statement. Set this variable to any value to activate it.

4

PYTHONHOME It is an alternative module search path. It is usually embedded in the PYTHONSTARTUP or PYTHONPATH directories to make switching module libraries easy.

Running Python

有三种不同的方法来启动 Python，如下所示 −

There are three different ways to start Python, which are as follows −

Interactive Interpreter

  1. You can start Python from Unix, DOS, or any other system that provides you a command-line interpreter or shell window.

  2. Enter python the command line.

  3. Start coding right away in the interactive interpreter.

$python # Unix/Linux
or
python% # Unix/Linux
or
C:> python # Windows/DOS

以下是所有可用命令行选项的列表，如下所示 −

Here is the list of all the available command line options, which is as mentioned below −

Sr.No.

Option & Description

1

-d It provides debug output.

2

-O It generates optimized bytecode (resulting in .pyo files).

3

-S Do not run import site to look for Python paths on startup.

4

-v verbose output (detailed trace on import statements).

5

-X disable class-based built-in exceptions (just use strings); obsolete starting with version 1.6.

6

-c cmd run Python script sent in as cmd string

7

file run Python script from given file

Script from the Command-line

可通过 invoking the interpreter on your application，在命令行中执行 Python 脚本，如下所示：

A Python script can be executed at command line by invoking the interpreter on your application, as in the following −

$python script.py # Unix/Linux

or

python% script.py # Unix/Linux

or

C: >python script.py # Windows/DOS

  1. Note − Be sure the file permission mode allows execution.

Integrated Development Environment(IDE)

如果系统上的 GUI 应用程序支持 Python，您还可以从图形用户界面 (GUI) 环境中运行 Python。

You can run Python from a Graphical User Interface (GUI) environment as well, if you have a GUI application on your system that supports Python.

  1. Unix − IDLE is the very first Unix IDE for Python.

  2. Windows − PythonWin is the first Windows interface for Python and is an IDE with a GUI.

  3. Macintosh − The Macintosh version of Python along with the IDLE IDE is available from the main website, downloadable as either MacBinary or BinHex’d files.

如果您无法正确设置环境，则可以向系统管理员寻求帮助。确保 Python 环境已正确设置，并且运行正常。

If you are not able to set up the environment properly, then you can take help from your system admin. Make sure the Python environment is properly set up and working perfectly fine.

  1. Note − All the examples given in subsequent chapters are executed with Python 2.4.3 version available on CentOS flavor of Linux.

我们已经在线设置了 Python 编程环境，以便您在学习理论的同时可以同时在线执行所有可用示例。随时修改任何示例并在线执行。

We already have set up Python Programming environment online, so that you can execute all the available examples online at the same time when you are learning theory. Feel free to modify any example and execute it online.