lambda, sorted, filter, map function recursively traverse a directory

1, lambda functions

lambda can only handle simple function

1  # a simple function 
2  DEF FUNC (X, Y):
 . 3      return X + Y
 . 4  # implemented by the lambda 
. 5  the lambda X, Y: X + Y

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2, sorted ranking function

function sorted
sorted function is ordered, is a sort iterable type of data, the general type of data to be iterable method of this sort, the custom function can be sorted ordering rules

#sorted函数的类型
sorted(iterable,key=none,reverse=False)

lst = [{"id":1,"name":"shuai","age":25},{"id":3,"name":"xiang","age":18},{"id":2,"name":"aoli","age":27}] 

# Age Sort 
L1 = sorted (LST, Key = the lambda dic: dic [ " Age " ])
 Print (L1)
 # by name alphabetical order 
L2 = sorted (LST, Key = the lambda dic: dic [ " name " ] [0])
 Print (L2)

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3, filter function

filter function

Which is determined by the function func iterable elements Meets

#filter(func,iterable)


lst = [19,20,18,30,25,17]
def func(age):
    return age >18

f = filter(func,lst)
print(f)
print("__iter__" in dir(f))
for i in f:
    print(i)

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4, map function

map mapping function

#map(func,iterable)

lst = [1,5,3,5,4,8,7,9]
l1 = map(lambda x : x**2,lst)
print(list(l1))

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5, recursive

　　The main feature is the recursive calls itself, the end must be specified, the deepest in the official said the number of recursive Python 1000

　　A recursive infinite loop　

= 1 ceng
 DEF Fun (ceng):
     Print (ceng) 
    Fun (ceng +1 ) 
Fun (ceng) 


operating results
 995 
996 
997 
998Traceback (MOST recent Results Last Call): 
  File " E: / python_iteam / LivePython / Day6 / directory / recursive .py " , Line 26, in <Module> 
    Fun (ceng) 
  File " E: / python_iteam / LivePython / Day6 / directory / recursive .py " , Line 25, in Fun 
    Fun (ceng +1 ) 
  File " E: / python_iteam / LivePython / day6 / directory / recursive .py " , Line 25, in fun
    fun(ceng+1)
  File "E:/python_iteam/LivePython/day6/目录/递归.py", line 25, in fun
    fun(ceng+1)
  [Previous line repeated 994 more times]
  File "E:/python_iteam/LivePython/day6/目录/递归.py", line 24, in fun
    print(ceng)
RecursionError: maximum recursion depth exceeded while calling a Python object

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　　By recursively through all the files in a folder

Import os
 DEF FUNC (file_dir, ceng): 
    
    list = the os.listdir (file_dir) # by os module to obtain directory below a directory to list indicates 
    for File in list: # circulation list, to distinguish between files and directories 
        file_path = os.path .join (file_dir, File) # get the absolute path 
        IF os.path.isdir (file_path):
             Print ( " \ t " * ceng + " % S: " % File) 
            FUNC (file_path, ceng +1) # recursive function 
        the else :
             Print ( " \ t "*ceng+"%s"%file)

func("F:\\",0)

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6, a binary search

The first, direct circulation

. 1 List = [1,3,4,5,6,8,9,10,24,34,45,54,63 ]
 2 Lift = 0
 . 3 right = len (List)
 . 4 n-int = (INPUT ( " Please enter a number: " ))
 . 5  the while Lift < right:
 . 6      MID = (+ Lift right) // 2
 . 7      IF List [MID]> n-:
 . 8          right = MID
 . 9      elif List [MID] < n-:
 10          Lift MID = . 1 +
 . 11      the else :
 12 is          Print ( " found a few% s, subscripts S% " %(List [MID], MID))
 13 is          BREAK 
14  the else :
 15      Print ( " List in this number is not " )

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The second, by a recursive function to create a new list

 1 list = [1,3,4,5,6,8,9,10,24,34,45,54,63]
 2 lift = 0
 3 right = len(list)
 4 n = int(input("请输入一个数："))
 5 def func(list,n):
 6     lift = 0
 7     right = len(list)
 8     mid = (lift + right)//2
 9     if mid > 0:
10         if list[mid] > n:
11             new_list = list[:mid]
12             func(new_list,n)
13         elifList [MID] < n-:
 14              new_list The List = [MID +. 1 :]
 15              FUNC (new_list The, n-)
 16          elif List [MID] == n-:
 . 17              Print ( " found a number S% " % List [MID])
 18      the else :
 19          Print ( " not found " )
 20 FUNC (List, the n-)

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Third, the recursive function is given about

 1 list = [1,3,4,5,6,8,9,10,24,34,45,54,63]
 2 lift = 0
 3 right = len(list)
 4 n = int(input("请输入一个数："))
 5 
 6 def func(list,lift,right,n):
 7     mid = (lift+right)//2
 8     if lift < right:
 9         if list[mid] > n:
10             right = mid
11             func(list, lift, right, n)
12         elif list[mid] < n :
13             lift = mid+1
14              FUNC (List, Lift, right, n-)
 15          elif List [MID] == n-:
 16              Print ( " found% s, position S% " % (List [MID], MID))
 . 17      the else :
 18 is          Print ( " not found " )
 19 FUNC (List, Lift, right, the n-)

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