python-Common built-in modules

Introduction to commonly used built-in modules
Os,sys,time,datetime,json/pickle,shutil,random

One. os

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1. Switch directories to see the current working directory OS.GETCWD

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2. Current directory, parent directory Os.curdir Os.pardir

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3. Create a directory Os.mkdir

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4. deleting files Os.remove

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5. Renaming Os.rename

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6. Execute shell command Os.system

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7. Return the directory and file name of the path os.path.split

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8. Determine if the specified object is a file, directory Os.path.isfile Os.path.isdir

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9. Get the size of the file , If it is a directory, return 0 os.path.getsize

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10. Connection directory and file name Os.path.join

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11. Determine if the directory exists os.path.exists

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Two. sys

1.sys.path is a list that indicates all paths to find Module,package

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2.SYS.ARGV is a list that contains all the command-line arguments

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3.sys.stdin.readline () reads a line of screen output from standard input a

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4.sys.modules is a dictionary that represents all the available module in the system

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5.sys.platform getting running operating system environment
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Three. Time

1.time.time (): Returns the timestamp of the current time

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2.time.localtime ([secs])
Converts a timestamp to the struct_time of the current time zone, which is the time array format

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3.time.gmtime ([secs])
Convert a timestamp to the struct_time of the UTC time Zone

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4.time.mktime (t): Converts a struct_time to a timestamp

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5.time.sleep (secs): Thread delays the specified time, the thread sleeps for a specified time, in seconds

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6.time.clock ()

This function returns the current CPU time with the number of seconds that the function calculates in floating-point numbers.

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7.time.asctime ()
A tuple or struct_time representing time is represented as a form of ' Thu Sep 7 14:31:59 2017 '. If no argument is given, Time.localtime () is passed in as a parameter.

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8.time.ctime ([secs])
Converts a timestamp (a floating-point number in seconds) into the form of time.asctime (). If you specify a parameter, Time.time () is used by default as the parameter.

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9.time.strftime (format [, T])

Format: Formatting strings

[t] optional parameter is a Struct_time object

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10.time.strptime (String[,format])
Converts a format string into Struct_time. The function is an inverse operation of the time.strftime () function. The time strptime () function resolves a timing string to a time tuple based on the specified format. So the function returns a Struct_time object.

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Four. DateTime

1. Get the current datetime

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2. Get Date of day

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3. Get tomorrow

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4. Three days before the current time

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5. Get the start and end times of the day (00:00:00 23:59:59)

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Five. Json/pickle

Son and Pickle module, two modules for serialization

-JSON module for conversion between string and Python data types

-Pickle module for conversion between Python-specific types and Python data types

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Six. Shutil

1.shutil.copyfile (SRC, DST) replication

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2.shutil.move (SRC, DST) move files or rename

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3.shutil.get_archive_formats () See which packaging formats are supported

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4.shutil.copymode (SRC, DST) just replicates its permissions other things are not copied

5.shutil.copystat (SRC, DST) copy permissions, last access time, last modified time

6.shutil.copy (SRC, DST) copy a file to a file or a directory

7.shutil.copy2 (SRC, DST) copy files on the basis of copy the last access time and modification time are also copied, similar to cp–p things

8.shutil.copy2 (SRC, DST) if the file system in two locations is the same, it is equivalent to rename operation, just renaming; if it's not the same filesystem, it's a move operation.

9.shutil.rmtree (SRC) recursively deletes a directory and all content within the directory

Seven. Random

1.random.random () is used to generate a 0 to 1 random character point

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2.random.uniform function to generate a random number of points in a specified range

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A function of 3.random.randint () to generate an integer within a specified range

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4.random.randrange's function prototype is: Random.randrange ([start], stop[, step]), gets a random number from the specified range, in the collection incremented by the specified cardinality

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5.random.choice gets a random element from the sequence.

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A 6.random.sample function that randomly fetches fragments of a specified length from a specified sequence.

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The 7.random.shuffle function is used to disrupt elements in a list

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python-Common built-in modules