interable

, which accepts optional key and reverse parameters Although you can use the fragment operator to access data items in a list, in some cases we need to extract two or more data items that can be implemented using sequence splitting. Any iteration (list, tuple, etc.) data type can be split using the sequence split operator, that is, *. For the two or more variables to the left of the assignment operator, one uses the * boot, the data item is assigned to the variable, and all the remain

the new hashmap definition directly. 2. Common ing operations Determines whether the ing contains a key: map. Contains (key value) 　　 Use + =VariableIngAdd element or join ing: 　　 Use-= removeVariableKey and corresponding element in ing 　　 You can use the + operator to return a new immutable ing. You can use the-operator to return a new immutable ing; 　　 Map Traversal 　　 Obtains the keyset and value set of the ing key set. 　　 By ingKeysetThe ing method can be used to obtain th

), range (5,1,-1)) print range (1,5) print Range (5,1,-1) PS: Common built-in module functions:ABS (x) returns the absolute value of XApply (Func[,args[,kwargs]]) put the parameters of the function in the sequence to pass in the functionBOOL ([x]) converts each value or expression to a bool type and returns True if the expression x is a value, otherwise falseCMP (x, y) compares the size of X, yDelattr (Obj,name) is equivalent to Del Obj.nameEval (S[,globals[,locals]]) evaluates the value of an

defined in deque. 9.1.5GenericsWhen designing an API, you can specify that a class or method supports generics, so that objects are re-played as a type, making the syntax more concise.9.1.6Lambda The lambda syntax expression omits the interface type and method name,-> left-hand column, the right is the method body 9.1.7Interable Interator Iterator () The Java.util.Interator method returns the operand of the interface, which can be used Hasnext () to see if there is n

list and returnsRaw_input ([prompt]) accepts input from the console and returns the string type.Reduce (func, sequence [, initial]) is used to accumulate the values of sequences.Round (x, n = 0) Rounding FunctionSet ([interable]) returns a setSorted (iterable [, cmp [, key [, reverse]) returns a sorted list.Sum (iterable [, start = 0]) returns the sumType (obj) returns the type of an object.The xrange (start [, end [, step]) function is similar to ra

,-1)) print range (1,5) print Range (5,1,-1) PS: Common built-in module functions:ABS (x) returns the absolute value of XApply (Func[,args[,kwargs]]) put the parameters of the function in the sequence to pass in the functionBOOL ([x]) converts each value or expression to a bool type and returns True if the expression x is a value, otherwise falseCMP (x, y) compares the size of X, yDelattr (Obj,name) is equivalent to Del Obj.nameEval (S[,globals[,locals]]) evaluates the value of an expressionFlo

1.any () functionAny (iterable)->boolReturns ture if one of the iterators is ture, or False if Interable=null.>>> any ([1,0])True>>> any ([0,0])False>>> any ([])False>>> any ([1,0,0])TrueApplication: In a binary tree, find the largest element in each layer (leetcode515).Input: 1 / 3 2 /\ \ 5 3 9 Output: [1, 3,9] #类节点的定义Classnode (self):def __init__(self,data) Self.val=Data Self.right=NULL Self.left=NULLcl

the syntax for lambda expressions omits interface types and method names. The left is the parameter column, and the right is the method body. The compiler can learn the syntax omitted information from the declaration of the request request. Although it is discouraged to use lambda expressions to write complex calculations, if the process is more complex and cannot be completed in a single line of lambda expressions, you can use the chunk {} notation to include the calculation flow. If the metho

new API, there is no such difference. Therefore, job configuration is completed through configuration, and sometimes some help methods (helper method) on the job may be required ). 7. the name of the output file is slightly different: the output files of MAP and reduce in the old API are named in part-nnnnn mode, in the new API, map output files are named by part-m-nnnnn, and reduce output files are named by part-r-nnnnn (counting starts from scratch ). 8. the new API requires that the method t

Functional programming makes code simple and efficient.Map function:Map (func, *iterables), which is the function of mapping a list to another list.class Map (object): """ Map (func, *iterables)--and map object make a iterator that computes the function using arguments from Each of the iterables. Stops when the shortest iterable is exhausted. """View CodeHow to use:def f (x): return x**2= range (1,10= map (f,li)print(res)print (List (res)) """ (+), +, +, +, Bayi] """M

1.mapmap()The first parameter passed in is the f function object itself.The map () function receives two parameters, one is a function, the other is Interable, and map passes the incoming function to each element of the sequence sequentially , returning the result as a new iterator.def f (x): ... return x*>>> r=map (f,[1,2,3,4,5])>>> list (R) [1, 4, 9, 16, 25]2.reducereduceTo function on a sequence [x1, x2, x3, ...] , the function must receive tw

: False19,isupper (self): Determines whether a string is uppercases = ' HELLO 'S1 = ' Hello 'result = S.isupper ()RESULT1 = S1.isupper ()Print (Result) Result: TruePrint (RESULT1) Result: False20,join (self, iterable): Splits the argument (interable) with a strings = ' HELLO 'result = S.join (' xxx** ')Print (Result) Result: xhelloxhelloxhello*hello*Ljust (self, width, fillchar=none) and rjust (self, width, fillchar=none) fills the specified width fro