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This article mainly explains "what are the useful skills of Python". Friends who are interested might as well take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "what are the useful skills of Python"?

Import module

Import declarations are often used in Python to use objects defined in other modules (that is, other .py files).

1) use _ _ name__

When we write Python library modules, we tend to run some test statements. When this program is import as a library, we do not need to run these test statements. One solution is to comment out the test statements in the module before import. A more elegant solution to Python is to use _ _ name__.

The following is a simple library program TestLib.py. When running TestLib.py directly, _ _ name__ is "_ _ main__". If import, _ _ name__ is "TestLib".

Def lib_func (a): return a + 10def lib_func_another (b): return b + 20if _ _ name__ ='_ _ main__': test = 101 print (lib_func (test))

We import the TestLib above in user.py.

Import TestLibprint (TestLib.lib_func)

You can try not to use if _ _ name__=='__main__', in TestLib.py and compare the results.

2) more ways to use import

Import TestLib as test # references the TestLib module and renames it t

For example:

Import TestLib as tprint (t.lib_func)

From TestLib import lib_func # refers only to lib_func objects in TestLib and skips the TestLib reference field

This has the advantage of reducing the memory footprint of the referenced module.

For example:

From TestLib import lib_funcprint (lib_func)

From TestLib import * # references all objects in TestLib and skips the TestLib reference field

For example:

From TestLib import * print (lib_func (120)) query

1) query the parameters of the function

When we want to know which parameters a function will accept, we can use the following method to query.

Import inspectprint (inspect.getargspec (func))

2) query the properties of objects

In addition to using dir () to query the properties of an object, we can use the following built-in (built-in) function to confirm whether an object has a property:

Hasattr (obj, attr_name) # attr_name is a string

For example:

A = [1, 2, 3] print (hasattr (a)

2) query the class and class name to which the object belongs

A = [1, 2, 3] print a.__class__print a.classic classrooms. Naming names _

3) query parent class

We can use the _ _ base__ attribute to query the parent class of a class:

Cls.__base__

For example:

Print (list.__base__) is in Chinese (and other non-ASCII codes)

Add # coding=utf8 to the first line of the Python program, for example:

# coding=utf8print ("how are you")

It can also be done in the following ways:

#-*-coding: UTF-8-*-print (how are you?) Represents binary, octal and hexadecimal numbers

In version 2.6 and above, expressed as follows

Print (0b1110) # binary, print (0o10) # octal starting with 0b, print (0x2A) # hexadecimal starting with 0o, starting with 0x

If it is an earlier version, you can use the following ways:

Print (int ("1110", 2)) print (int ("10", 8)) print (int ("2A", 16)) Notes

Comments on one line can start with #

Multi-line comments can start with''and end with'', such as

'' This is demo'''def func (): # print something print ("Hello world!") # use print () function# mainfunc ()

Comments should be aligned with the block in which they are located.

Search path

When we import, Python will find the module (module) in the search path. For example, the above import TestLib requires that TestLib.py be in the search path.

We can view the search path in the following ways:

Import sysprint (sys.path)

We can add or remove elements from the sys.path while Python is running. On the other hand, we can increase the search path for shell by adding the PYTHONPATH environment variable to Python.

Let's add / home/vamei/mylib to the search path:

$export PYTHONPATH=$PYTHONPATH:/home/vamei/mylib

You can add the positive command to ~ / .bashrc. In this way, we have changed the search path for a long time.

Combine script with command line

You can run a Python script using the following method, and when the script is finished, go directly to the Python command line. The advantage of this is that the object of the script will not be emptied and can be called directly from the command line.

$python-I script.py

Install non-standard package

Python's standard library is installed with Python. When we need non-standard packages, we have to install them first.

1) use Linux repository (Linux environment)

This is a good starting point for installing Python add-on packages. You can look for possible Python packages in Linux repository (such as searching for matplot in Ubuntu Software Center).

2) use pip. Pip is a package manager that comes with Python that connects to Python repository and looks for packages that may exist in it.

For example, use the following methods to install, uninstall, or upgrade web.py:

$pip install web.py

$pip uninstall web.py

$pip install-upgrade web.py

If your Python is installed in a non-standard path (use $which python to confirm the path of the python executable file), for example, in / home/vamei/util/python/bin, you can use the following method to set the path of the pip installation package:

$pip install--install-option= "--prefix=/home/vamei/util/" web.py

3) compile from source code

If none of the above methods can find the library you want, you may need to compile from the source code. Google is often the best place to start.

At this point, I believe you have a deeper understanding of "what are the useful skills of Python"? you might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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