Introduction to some common modules in Python

The module is essentially a. py file, which you can see under the Lib folder in the installation directory

Modules are divided into three parts: built-in modules (in the interpreter), third-party modules (under Lib folder), custom modules (defined by themselves)

1.time Module

Import time# Returns the timestamp of the current time print (Time.time ()) #1498027773.1063557# takes a timestamp as a parameter, returns a structured time tuple, and the parameter defaults to the current time print (Time.localtime ( 1912412470)) #time. Struct_time (tm_year=2030, tm_mon=8, Tm_mday=8, tm_hour=17, tm_min=41, tm_sec=10, tm_wday=3, Tm_yday =220, tm_isdst=0) #以时间戳为参数, returns the structured GMT, the default parameter is the current time print (Time.gmtime ())    #time. Struct_time (tm_year=2017, tm_mon= 6, tm_mday=21, tm_hour=6, tm_min=49, tm_sec=2, tm_wday=2, tm_yday=172, tm_isdst=0) #结构化时间转化成字符串时间print (Time.strftime (' %y:%m:%d-%x ', Time.localtime ()))   #2017:06:21-14:48:50# string time into formatted time print (Time.strptime (' 1993-10-15 ', '%y-%m- %d ')  #time. Struct_time (tm_year=1993, tm_mon=10, tm_mday=15, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=4, tm_yday= 288, Tm_isdst=-1) #结构化时间转换成时间戳print (Time.mktime (Time.localtime ())) #1498027859.0print (Time.asctime ())   #Wed June 14:53:11 2017print (Time.ctime ())     #Wed June 21 14:53:11 2017# thread delays the specified time, the parameter is the specified number of seconds Time.sleep (5)

Conversion of several time forms:

2.random Module

Floating point  0.40165771797504246print (Random.randint (1,3)) between import Randomprint (Random.random ()) #随机返回一个 (0,1)  # Randomly returns a specified range [1,3] int type  3print (Random.randrange (1,3)) #随机返回一个指定范围 [1,3] int type  1print (Random.choice ([ 12,21,23,34, ' A ', ' B ']) #随机返回一个指定列表中的元素  12print (Random.sample ([12,21,23,34, ' A ', ' B '],3)) #随机返回指定个数的指定列表中的元素  [' A ', +, ' B ']print (Random.uniform (1,3)) #随机返回一个 (1,3) floating-point number    2.2162483038520144l=[1,2,3,4,5,6] Random.shuffle (L)   #把指定列表的顺序打乱print (L)    #[1, 3, 6, 2, 4, 5]

Practice

#练习, randomly generate a 5-bit verification code, including numbers, uppercase and lowercase letters import randomres= ' for I in Range (5):    num=random.randint (0,9)    ALPA=CHR ( Random.randint (65,90))    alpa=chr (Random.randint (97,122))    s=random.choice ([str (num), Alpa,alpa])    Res=res+sprint (RES)

3.os Module

 1 Import OS 2 3 #获取当前工作目录 4 print (OS.GETCWD ()) #C: \untitled\0621day12 5 6 #改变当前工作目录, equivalent to CD 7 Os.chdir (File_path) in the shell 8 9 #生成多层递归目录10 os.makedirs (' dirname1/dirname2 ') #递归删除空目录13 os.removedirs (path) #生成单级目录16 os.mkdir (' dirname ') #删除单级空目录, the directory is not empty can not delete the Os.rmdir (path) #列出指定目录下的所有文件和子目录, including hidden files, printed in a list print (Os.listdir (R ' C:\untitled\ 0612Python Fifth day ')) #[' 0612 jobs. Py ', ' a.txt ', ' Job title ', ' character encoding. Py ', ' file operation. py ']23 #删除一个文件25 os.remove () #重命名文件/catalogue Os.ren Ame (' oldname ', ' newname ') #获取文件/directory information Os.stat (path) print (Os.stat (R ' C:\untitled\0612Python fifth Day ')) #os. Stat_ Result (st_mode=16895, st_ino=2814749767244350, st_dev=3504670893, St_nlink=1, St_uid=0, St_gid=0, st_size=4096, St_ atime=1497356489, st_mtime=1497356489, st_ctime=1497227714) #返回文件目录, is actually the first element of Os.path.split (path) 35 Os.path.dirname (Path) #返回文件的文件名, is actually the second element of Os.path.split (path), Os.path.basename (path) #如果path以/or \ End, will return a null value 39 #如果文件存在, returns True if the False41 os.path.exists (path) #如果path是绝对路径 is returned, and the TRue44 os.path.isabs (path) #将多个路径组合后返回, parameters before the first absolute path will be ignored Os.path.join (path,paths) 48 49 # Returns the last access time of the file or directory that the path points to (path) Os.path.getatimme #返回path所指向的文件或目录的最后修改时间53 os.path.getmtime (path) 54 55 # Returns the size of path, os.path.getsize (path)

4.hashlib

The Hashlib module provides a common digest algorithm, such as MD5,SHA1, in Python3, where the hash directly replaces the MD5 and SHA

Abstract the algorithm is a function, the arbitrary length of the data into a fixed length of the data string.

1. Abstract the algorithm is irreversible and cannot be reversed by the data string to get the meta-data

2. Two data, even if only 1bit difference, get the summary is not any relationship

3. Regardless of the size of the metadata, the resulting digest is fixed-length

4. When the metadata is large, you need to read one line at a time, and then one line of validation, and the last. Hexdigest () can get a summary of all previous results

MD5 is very fast and very common, and the resulting result is a fixed 128bit usually represented by a 32-bit 16 binary string.

Import hashlibmd5=hashlib.md5 () md5.update (' Aasg '. Encode (' Utf-8 ')) #434c591c9c5a04e44ec8dbafe81058e7md5. Update (' ADASDG '. Encode (' Utf-8 ')) #d20a55b2194493fdeb66e2cd358dab15md5. Update (' AASGADASDG '. Encode (' UTF8 ')) # D20a55b2194493fdeb66e2cd358dab15print (Md5.hexdigest ())

Not to be continued ....