Python Common libraries

A. Standard library, time datetime two standard library
1.time and datetime 1) timestamp 2) format time 3) Ganso (struct_time) Total nine elements, time.localtime () tuple data

UTC GMT China utc+8 eight hours earlier than standard time


Time () get timestamp
Gmtime () Time to convert time to UTC time zone
LocalTime () The current timestamp is converted to a tuple. or the meta-group information of the time stamp passed in

Time stamp
Timestamp to tuple gmtime (time)-to UTC time zone
LocalTime (Time)--current TimeZone

Tuple to timestamp mktime (time) to convert tuples to timestamps


Convert tuples to formatted string strftime ('%y-%m-%d ', (tuple time))
Convert time format to meta-ancestor strptime ("2017-07-16", "Time format") returns a time tuple

Asctime (accepts tuple data) CTime (time stamp is passed in)


Datetime.datetime.now () Gets the current time with Datetime.timedelta (3) using the current time corresponding to the 3 day-+3 or hours=3
Calculate the first three days or three hours before, three years, etc.


B Random floating-point standard library



C OS Module
OS.GETCWD () Gets the current working directory,
Os.chdir ("CC") changes the current script working directory

D SYS system module
Pring (SYS.ARGV 1234) Get parameters

E shutil File Operation module

F JSON pickle Module
JSON primarily serializes the conversion between user strings and Python data types
Dumps dump loads load
Pickle function dumps dump loads load Python-specific modules
G shelve module, simple kv memory data through the file persistence module, you can persist any pickle can support the Python data format


H XML Processing Module
Import Xml.etree.ElementTree as ET introduces XML processing module

Python Common libraries