The path of Python development--8

One, Module 1. module

(1) Definition: A. py file is a module

(2) Reason: In order to prevent the program code getting longer, the functions are grouped into different folders.

(3) Advantages: Improve the maintainability of the code, the module can be written to be referenced by others, you can also refer to other modules; You can avoid conflicting variable names and function names

(4) Module type: A total of three kinds of ①python standard library; ② third-party module; ③ Application custom Module

2. Module Import method

The essence of module import: by Sys.path find the function to import and execute the script, the (1) method loads the variable name into the variable space, (2) loads the variable name in

(1) Import statement

Import Timetime.sleep (2) Print ("OK")

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(2) From...import statement

 from Import  = cal ($)print(res)

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(3) from...import* statement

 from Import *# does not recommend this method, it is possible to overwrite the function defined by itself (function is variable)res1 =cal (2,3 = sub (4,2) Print (Res1,res2)

View Code3. Package

In order to avoid the module conflict, according to the directory to organize the module, this directory will be delivered, the package directory will have a __init__ file, which is the difference between the package and the normal folder

All modules below the package will not conflict as long as the top-level package name does not conflict

Multilayer Package Reference

 from Import  = cal ($)print(res)

View Code4. Test code

if __name__= ="__main__":

Two features: 1. Display "__main__" in the execution code; 2. Display the name of the file in the calling module

(1) function one: When debugging the code, add, when the module is called from another. py file, the contents of debugging are not displayed

def cal (x, y  ): return (x+y) def Sub (x, y    ): return (xy) if __name__= ="__main__"    :print ("  OK")

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(2) function Two: In the execution of code, to prevent their own logic code is called by others

Second, time module 1. Timestamp

Import  Time Print (Time.time ()) # Timestamp number of seconds, starting from the early 1970, the birth time of Unix

View Code2. Structured time

Import  Time Print (Time.localtime ()) # local time Print (Time.gmtime ()) # UTC Time

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Convert structured time to timestamp

Import  Time Print (Time.mktime (Time.localtime ()))

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Convert structured time to string time

Import  Time Print (Time.strftime ("%y-%m-%d  %x", Time.localtime ()))

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3. String time

Import= time.localtime ()print(time.asctime (t))Print (Time.ctime (1124324))

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Convert string time to structured time

Import  Time Print (Time.strptime ("2018-5-11 21:01:26","%y-%m-%d%x"))

View Code4.time.sleep () and Time.clock ()

Time.sleep () Delays the specified time run, in seconds

The Time.clock () function returns the current CPU time in seconds calculated as a floating-point number. It is more useful than time.time () to measure the time spent on different programs. It is important to note that the meanings are different on different systems. On a UNIX system, it returns "process time", which is a floating-point number (timestamp) in seconds. In Windows, the first call returns the actual time that the process is running. The second subsequent call is the elapsed time since the first call to the present. (actually based on QueryPerformanceCounter () on WIN32, which is more accurate than milliseconds)

Import  Time Print (Time.clock ()) Time.sleep (2) Print (Time.clock ())

View Code5.datetime Module

Show Current Time

Import datetime Print (Datetime.datetime.now ())

View CodeThird, random module

The random module mainly has the following functions

ImportRandomPrint(Random.random ())#randomly generate a floating-point number less than 1Print(Random.randint (1,3))#randomly generates an integer that can be taken to 3Print(Random.randrange (1,3))#randomly generates an integer that takes less than 3Print(Random.choice ([11,22,33,44]))#randomly select a number from a listPrint(Random.sample ([11,22,33,44],2))#randomly select two numbers from a listPrint(Random.uniform (1,4))#generate floating-point numbers within a specified rangeret = [1,2,3,4,5]random.shuffle (ret)#Scramble OrderPrint(ret)

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Generate Verification Code

Import Random def V_code ():     ""     for  in range (4):        = Random.randint (0,9)        = Chr (Random.randint (65,90))        = Str (random.choice ([Num,letter])        + = s    return  ret Print (V_code ())

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The path of Python development--8