Python Base Four, pythonbasefour

Python Base Four, pythonbasefour

35. In python, file operation syntax is similar to c.

Open (file, 'R ',......) // The first parameters is necessary, other is optional, the second parameters is 'R' by default

If you want to open a file, you can use:

F = open ('// Users // wyg_mac // Desktop // Account.txt') // if you don't know the path, you can drag the file to console

If you want to close file, you can use:

F. close ()

Next now that we know how to open file and close file, but how to read file content.

You can use

F. read (size =-1) // read size buffer, if size not define or minus, read next buffer, and return as string

F. readline () // open as write mode, if file exist, append at end

If you want to write content to file, how to achieve it.

F. wirte (str) // put str write file

F. wirtelines (seq )//

F. tell () // return current position

F. seek (offset, from) // from (if is 0, start position, 1 current position 2 end position) offset

Such as if I want to create a file demo.txt on desktop and write content whth 'write code change world'

F = open (R'/users/wyg_mac/desktop/demo.txt ', 'w ')

F. wirte ('write code change World ')

F. close ()

There are something we need to notice:

If a file not exist, as follow, it will have error:

F = open (R'/users/wyg_mac/desktop/a.txt ')-> error

If file not exist, you use follow it will be right:

F = open (R'/users/wyg_mac/desktop/a.txt ')-> right

 

// Seventh day to study python

36. In python, OS module is base and important.

Import OS

OS. getcwd () // get current file path

-> '/Users/wyg_mac/documents'

OS. chdir ('/users/wyg_mac/desktop') // change file path

OS. getcwd ()

-> '/Users/wyg_mac/desktop

OS. listdir ('/users/wyg_mac/desktop') // list file dir

-> Choose 'demo.txt ','. DS_Store ',]

OS. mkdir ('/users/wyg_mac/desktop/')

-> Create a file named

OS. mkdir ('/users/wyg_mac/desktop/a/B ')

-> If file a exist, create file named B in file a, if a not exist, will have an error

OS. makedirs ('/users/wyg_mac/desktop/m/n/o ')

-> Create file m on desktop, m include n, n include o

If file m/n/o, o include ttt.txt

OS. remove ('/users/wyg_mac/desktop/m/o/ttt.txt ')

-> Remove ttt.txt according to path

OS. rmdir ('/users/wyg_mac/desktop/m/n/o ')

-> Remove o file, if o contain content, error, if not, remove it.

OS. removedirs ('path ')

->

OS. rename ('/users/wyg_mac/desktop/A','/users/wyg_mac/desktop/aaa ')

-> Change file name

OS. system (command)

-> Command is shell command, such as OS. system ('cmd ')

OS. curdir // current

->.

OS. pardir //

-> ..

Such:

OS. listdir (OS. curdir '= OS. listdir ('.')

OS. sep // current OS path sep

->/

OS. name // current OS name

-> 'Posix'

 

37. OS. path

OS. path. bastname ('/users/wyg_mac ')

-> Wyg_name

OS. path. dirname ('/users/wyg_mac/desktop ')

-> Users/wyg_mac

OS. path. join ('/users', 'wyg _ mac', 'desktop ')

-> '/Users/wyg_mac/desktop'

OS. path. split ('/users/wyg_mac/desktop/m/N ')

-> ('/Users/wyg_mac/desktop/m', 'n ')

OS. path. splitext ('/users/wyg_mac/desktop/m ')

-> ('/Users/wyg_mac/desktop/m ','')

OS. path. splitext ('/users/wyg_mac/desktop/m.txt ')

-> ('/Uses/wyg_mac/desktop/m', '.txt ')

OS. path. getsize ('/users/wyg_mac/desktop/m.txt ')

-> 35

OS. path. getctime ()

OS. path. getmtime ()

OS. path. getatime ()

OS. path. mtime ('/users/wyg_mac/desktop/m ')

-> 1470748934.0

If you don't understand it, you can use:

Import time

Time. localtime (OS. path. getmtime ('/users/wyg_mac/desktop/m '))

-> Time. struct_time (tm_year = 2016, tm_mon = 8, tm_mday = 9, tm_hour = 21, tm_min = 22, tm_sec = 14, tm_wday = 1, tm_yday = 222, tm_isdst = 0

OS. path. exists ('/users/wyg_mac/desktop/m ')

-> True

OS. path. isabs () // if abs path

OS. path. isfile ()

OS. path. isdir ()

OS. path. ismount ()

OS. path. islink ()

OS. path. samefile (,)

 

38. pickle module, you can store data to file and read it

Import pickle

My_list = [123, 3.14, 'roy '[1, 3]

Pickle_file = open('my_list.txt ', 'wb ')

Pickle. dump (my_list, pickle_file)

Pickle_file.close ()

 

Pickle_file = open('my_list.txt ', 'rb ')

My_list2 = pickle. load (pickle_file)

Print (my_list2)

-> [123, 3.14, 'roy ', [1, 3]