List: Data structure for handling a set of Ordered items 1, list operator List1=[2,3,4,5,6,7,8]print len (list1) print [1,2]+[3,4]print [' Hi ']*4print 4 in List1for I in List1:print ilist2=list1list3=list1[:]print list2 are list1 trueprint list3 is list1 falseshoplist = [' Apple ', ' MONGO ', ' Carrot ', ' banana '] 2, new element shoplist.append (' rice ') print U ' new shopping list ', shoplist result: New shopping list [' Apple ', ' MONGO ', ' carrot ', ' Banana ', ' rice '] 3, delete an element List1=[1,2,3,4,5,6,7]list1.remove (3) value operation, no return value del list1[2] subscript operation List1.pop (2) subscript operation, with return value 4, compares elements in two lists for equality CMP (LIST1,LIST2) 1,0,-1 return value List1 = = List2str (list1) = = str (list2) 5, remove the largest element in the list: two methods Max ( List1) List1.sort () list1[-1] 6, insert an element List1.insert (2,1024) Insert 1024 element 7, merge list lista=[1,2,3]listb=[in place labeled 2 9,4,5]lista.extend (LISTB) or ListA = Lista+listbprint ListA Result: [1, 2, 3, 9, 4, 5] 8, two-dimensional list listc=[[1,2,3],[21,22,23]] Print U ' first element ', Listc[0]print u ' first element ', listc[0][0] Result: first element [1, 2, 3] first element 1 9, statistic list [1,2,3,4,5,6,3,4,5,6,3] 3 occurrences , not less than two methods List1.count (3) sum=0for i in list1:if i = = 3:sum +=1print sum 10. Determine if a variable belongs to a class if Isinstance (listc,list):p rint ' OK ' result: OK or: if Type (LISTC) = = list: 11, reverse list list1=list (reversed (List1)) List1.reverse () directly modifies the List1 and does not need to assign a value to the List1 list1=list1[::-1] get the subscript of the element List1.index (454) for I in Xrange (Len (list1)): If list1[i] = = 454:print Ibreak Second, advanced application 1, slice Description: Lista[startponit:endponit:step (step)], after slicing to get a new list Startpoint:endpoint Front closed (1) Slicing operation, very important lista=[1,2,3,4,5,6] print Lista[0:4] results: [1, 2, 3, 4] print Lista[0:4:2] Results: [1, 3] (2) step is negative, which enables reverse output print lista[::-1] Results: [6, 5, 4, 3, 2, 1] 2, List changed to String listb=[' a ', ' B ', ' C ']print '. Join (LISTB) Results: abc 3, List Builder (1) The first range (A:B:C) list1=range () Print list1 results: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] list2=range (2,10) p Rint list2 Results: [2, 3, 4, 5, 6, 7, 8, 9] list3=range (2,10,2) Print list3 results: [2, 4, 6, 8] (2) The second type of list4=[x*x for x in RA Nge (]print) list4 results: [0, 1, 4, 9, A, A-Z,, $, a, 81] LIST3 = [m+n for M in ' ABC ' for n ' XYZ '] results: AX,AY,AZ,BX, By,bz,cx,cy,cz list1 = [1,2,3,4]LIST2 = [2*i for i in LIst1 if i>2] list3 = [m+n for M in ' ABC ' for n ' XYZ '] dict4 ={' x ': ' A ', ' y ': ' B ', ' Z ': ' C '}list4 = [k + ' = ' +v for K,v in Dict4.items ()] l = [' Hello ', ' World ', ' IBM ', ' Apple ']list5 = [S.lower () for S in L] 4, sort () method sort (cmp=n ONE,KEY=NONE,REVERSE=FALSE) CMP: Default by ASCII value comparison, can be defined using other values for comparison CMP: For a custom comparison function, accept two parameters, and if the first argument is less than the second argument, returns a negative number, is greater than returns an integer, and so on returns 0. The default value is None. Key: An element in the default list. From what to compare, you can customize the function Key's usage scene to compare multiple reverse: Default ascending, Reverse=true, reverse eg:list1=[(1,5,3), (1,1,2,3,4), (1,6)]def L (tup): Return Len ( TUP) List1.sort (key=l,reverse=true) Print list1 eg:list1 = [( -1,5,3), ( -5,3,6,3), (1,1,2,4,5,6), (2,9), ( -2,10)], Use the tuple's first element size comparison to sort the list, in reverse order. List1 = [( -1,5,3), ( -5,3,6,3), (1,1,2,4,5,6), (2,9), ( -2,10)]def L (TUP): Return abs (Tup[0]) List1.sort (cmp=cmp,key=l, reverse=true) Print list1
Data structure of Python: list
