Python Learning Note 11 _ function returns multi-valued, list-generated, loop-multivariate, parameter-in-format declarations

One, function returns multiple values

1, if the function returns multiple values, it will put these values into a tuple
2, if the function returns more than one value, you can also use multiple variables to receive

def say ():     = 1    = 2    = 3    return  num1,num2,num3print#  If a function returns multiple values, it will put these values in a tuple, (1, 2, 3)Res1,res2,res3 = Say ()# When multiple values are returned, print can be received with multiple variables   #1print#2print#3

ii. List-generated

L = [I for I in Range (1,101,2)]

List-generated, can only be used in the list

Write the loop first, and then take the I out of the loop, you can do some simple operations (0, convert to string, etc.)

Import= random.sample (range (1,34), 6= []# for num in red_num:#       tmp = str (num). Zfill (2)#     new_num.append (TMP)for in Red_num]# List-generated print(new_num)#[' 16 ', ' 20 ', ' 07 ', ' 18 ', ' 13 ', []

Generate an odd number within 100

 for  in range (1,101,2)]# outside is [] is a listprint(l)

third, generator

L1 = (I for I in range (1,11,2))

Replace [] in list generation with (), the print generator itself will display generator instead of list

L = [i forIinchRange (1,11,2)]#outside is [] is a list#Space change time, memory consumption is large, but no longer CPU#list It is to put all the elements in the memory, here will apply for 5 memory spacePrint(l)#[1, 3, 5, 7, 9]L1 = (i forIinchRange (1,11,2))#outside is () the word is generator#The Generator generator saves memory than the list, it is the time of each loop, it calculates an element according to the rule, and puts it into memory .#generator performance is better than the list, only a piece of memory space, each call and then go according to the rules to calculatePrint(L1)#<generator Object <genexpr> at 0x00000000030fe4c0> forIinchL1:Print(i)#1 3 5) 7 9

four or three meta-expressions

c = A If a > b else b

A = 5= 3#  If a > B:#     c = a#  Else:# C10/>c = bifelse# If A is greater than B, a = c, otherwise c =bprint(c)

v. Cyclic two-dimensional arrays

L = [    [1,2,3,4],    ['a','b','C','D']] forA,b,c,dinchL#There are multiple elements in a two-dimensional array that can be looped    Print(a)#1,a    Print(b)#2,b

Vi. declaration into the parameter format

Simply for code readability, and does not force the conversion type

def My (name:str):# tells others that name is STR but does not force conversions, L:list tells others to pass in the list   print( Name) my ('hello') my (['123', 123]# Enter the parameter is list also can, [' 123 ', 123]

Python Learning Note 11 _ function returns multi-valued, list-generated, loop-multivariate, parameter-in-format declaration