Python's common modules

Module:

The module is essentially a Python file that writes the Python code inside the module.

Module Categories:

Standard library: Python built-in

Open Source module: third party

Custom modules: Write your own

One, OS, sys module

ImportOS, sysPrint(OS.GETCWD ())#Get current directoryOs.chmod ("/usr/share", 7)#Add permissions to the/usr/share directoryPrint(Os.curdir)#current directoryPrint(Os.pardir)#Parent DirectoryPrint(Os.makedirs ("/usr/local/mysql"))#Create a directory recursively when the parent directory does not existPrint(Os.removedirs ("/usr/local/mysql"))#recursively delete empty directoriesPrint(Os.mkdir ("New"))#Create a folderOs.rename (" Old","New")# RenamingPrint(Os.path.join ("/root",'MySQL','Rack.sql'))#stitching into a pathPrint(Os.path.split ("/usr/mysql/123.txt"))#split path and file namePrint(OS.SEP)#path delimiter for current operating systemPrint(OS.LINESEP)#line breaks for the current operating systemPrint(OS.PATHSEP)#The delimiter for each path in the current system's environment variables, Linux is:, Windows is;  Print(Os.environ)#environment variables for the current systemPrint(Os.path.abspath (__file__))#Get absolute pathPrint(sys.version)#Get System versionPrint(SYS.ARGV)#command line Arguments list, the first element is the path of the program itselfPrint(Sys.path)#returns the search path for the module, using the value of the PYTHONPATH environment variable when initializingPrint(Sys.platform)#returns the operating system nameSys.stdout.write ('Please :')#output A Word to the screenPrint(sys.maxsize)#Maximum Value

Second, random module

Importrandom, StringPrint(Random.random ())#Random floating point number, default is 0~1, cannot specify range of valuesPrint(Random.randint (1,18))#randomly take integersPrint(Random.randrange (1,28))#randomly produces a rangePrint(Random.choice ('sjdkf93f')#random selection of an elementPrint(Random.sample ('Hello', 3))#randomly take 3 of elementsPrint(Random.uniform (1, 9))#Random floating point number, you can specify the range of valuesF= [1, 2, 3, 4, 5]random.shuffle (f)#Scramble OrderPrint(f)Print(string.ascii_letters+string.digits)#all the numbers and letters

Three, Time&timedate module

There are three ways to represent time, one is timestamp, one is format time, one is time tuple

ImportTime , TimedatePrint(Time.timezone ())#time difference from standard time, unit is SPrint(Time.time ())#gets the current timestampPrint(Time.sleep (1))#rest 1sPrint(Time.gmtime ())#convert timestamp to time tuple, default time stamp for standard Time zone if not passedPrint(Time.localtime ())#Converts the timestamp to a time tuple and, if not passed, the timestamp of the current time zone by default

Print(Time.mktime (Time.localtime ()))#convert a time tuple to a timestampPrint(Time.strftime ("%y%n%d%h%m%s"))#convert a time tuple to a formatted output stringPrint(Time.strptime ("20170908 182719","%y%m%d%h%m%s"))#convert formatted time to a time tuplePrint(Datetime.datetime.now ())#current time formatted output       Print(Datetime.datetime.now () +datetime.timedelta (3))#3 days from the time       Print(Datetime.datetime.now () +datetime.timedelta (-3))#3 days before the time

Python's common modules