# Lambda, list-generated, dictionary-to-list ordering

Source: Internet
Author: User

1. function returns multiple values:

1) If the function returns multiple values, the returned values are placed in a tuple

`def say ():     = 1    = 2    = 3    return= say ()print( RES)>>> (1, 2, 3)`

2) function if you return multiple values, you can use multiple variables to receive each

`def say ():     = 1    = 2    = 3    return= say ()print(res1)   #>>>1print(res2)   # >>>2 Print (RES3)   # >>>3`

2, Lambda: anonymous function, function is simple, use only once, do not need to define

`Lambda x:x+1  # before the colon is the return value, the colon is followed by the function body, and the function's processing logic Print(res (1))> >> 2`

3. List-generated (list)

` for  in range (1,101,2-inif i%2==1]  # or write like this  print(l)>>>[1, 3, 5, 7, 9 ...]`

if the form outside of the list generation is ():L is not a list , but a generator

` for inch if i%2==1)print(l)  #L is a generator #print (l.__next __ ())   #生成器调用一次取一个值for in  L:       print(i)>  >> <generator Object <genexpr> at 0x00bfd8c8>>>>1 3 5 7 9 ...`

# each time the generator loops, it calculates only one element per rule, in memory, than the list save memory

#list is to put all the elements in memory.

4, three-dimensional expression

`A = 5= 4ifelse b   # ternary expression print= 5  = 4if a>B:    = aelse:    = b  Print(c)`

5, the dictionary is unordered, directly to the dictionary sort does not exist. First, turn the dictionary into a list and sort

#sorted (): Automatically loops through the elements inside a two-dimensional array

`D = {'a'75A'b': 2,'C': 3}Print(D.items ())#get a two-dimensional arrayres = sorted (D.items (), key=LambdaX:x[0])#The key value of the key= dictionary, sortedRes= Sorted (D.items (), key=LambdaX:X[1])#sort based on the value of the dictionaryPrint(RES)>>> Dict_items ([('b', 2), ('a', 5), ('C', 3)])>>> [('a', 5), ('b', 2), ('C', 3)]`

To loop, take multiple:

`L = [[1,2,3],[3,4,5],[5,6,7]] for in L:  #a,b,c is 3, Each of the above small list contains 3 elements?     Print(a,b,c)`

6, when defining the function, tell others what type of argument should be passed

`def is_float (S:STR):     Pass`

Lambda, list-generated, dictionary-to-list ordering

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