Python knowledge points, small usage

1. Anonymous function lamdba x:x**2def f (x):     return x**2g = lambda x:x**2     print map (F,range ())     print map (g,range) 2.map function     print map (F,range (Ten))     print map (G,range (10)) 3. Sort function sorted    dic1 = {        9:2,         4:6,        8:1,          ' a ': 10    }    print dic1     print  sorted (Dic1.items ())     print  sorted ( Dic1.items (), key=lambda x:x[0])     print  sorted (Dic1.items (), Key=lambda &NBSP;X:X[1]) 4. Iterator Http://www.liaoxuefeng.com/wiki/0014316089557264a6b348958f449949df42a6d3a2e542c000/ 00143178254193589df9c612d2449618ea460e7a672a366000 iterators only record a start, and an end, and the current position, each cycle one step down the benefits: Save memory empty Where: Xrange (), Xreadlines () import timedef  Run ():    print  ' test 1 '     time.sleep (1)      yield 1   # #这个相当于reture  1  But yield 1  words, when you execute X.next again () You can also come back from this place and start doing the following until you encounter the next yield and then exit                  #  Reture After exiting is unable to return to perform the following content     print  ' test 2 '      time.sleep (1)     yield 2    print  ' test  3 '     time.sleep (1)     yield 3    print   ' Test 4 '     time.sleep (1)     yield 4     print  ' test 5 ' Task = run () task.next () print  "--------do sth 1 --- --------"Task.next () Print&nbsP; " --------do sth 2 -----------"Task.next () print "--------do sth 3 ----------- "Task.next () print "--------do sth 4 -----------"Task.next () print "--------Do sth  5 -----------"Task.next ()     # #这个时候会出现StopIteration报错 # #好处, You can have it and the main program switch back and forth to invoke other content 5. Regular Expression >>> import re>>> a =  ' asdasd3as9#23_454/45 (*_dfdf_\\~r) 3 ' >>> m = re.search (' DFD ', a) >>> print  m<_sre. Sre_match object at 0x10221a030>>>> print m.group () dfd>>>> >>>>> m = re.findall (' [a-za-z]+ ', a)   # #查找所有字母, tuple format returned >>>  print m[' asdasd ',  ' as ',  ' dfdf ',  ' R ']>>>>>>>>> m  = re.split (' \d+ ', a) >>> print m[' asdasd ',  ' as ',  ' # ',  ' _ ',  '/' ,  ' (*_dfdf_\\~r) ',  ']>>&Gt;>>>>>> m = re.sub (' \d+ ', "|", a,count=3) &GT;&GT;&GT;&NBSP;PRINT&NBSP;MASDASD |AS|#|_454/45 (*_dfdf_\~r) 3>>>>>> a ' Asdasd3as9#23_454/45 (*_dfdf_\\~r) 3 ' >>>> >> a= ' 192.173.12.121 '    # #匹配ip >>> a ' 192.173.12.121 ' >>>  Re.search (' (\d+) (\.\d+) {3} ', a). Group () ' 192.173.12.121 ' 6. Recursive function Def calc (n):     print   '-------------> ',n    if n > 0:         calc ((N/2)) Calc (-------------> 20-------------> 10------------->  5-------------> 2-------------> 1-------------> 0

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Python knowledge points, small usage