Learning---python learning with built-in functions

Built-in functions

"Py3.5 Official Document" Https://docs.python.org/3.5/library/functions.html#abs

	Built-in Functions
ABS ()	Dict ()	Help ()	Min ()	SetAttr ()
All ()	Dir ()	Hex ()	Next ()	Slice ()
Any ()	Divmod ()	ID ()	Object ()	Sorted ()
ASCII ()	Enumerate ()	Input ()	Oct ()	Staticmethod ()
Bin ()	Eval ()	Int ()	Open ()	STR ()
BOOL ()	EXEC ()	Isinstance ()	Ord ()	SUM ()
ByteArray ()	Filter ()	Issubclass ()	POW ()	Super ()
Bytes ()	Float ()	ITER ()	Print ()	Tuple ()
Callable ()	Format ()	Len ()	Property ()	Type ()
Chr ()	Frozenset ()	List ()	Range ()	VARs ()
Classmethod ()	GetAttr ()	Locals ()	Repr ()	Zip ()
Compile ()	Globals ()	Map ()	Reversed ()	__import__ ()
Complex ()	Hasattr ()	Max ()	Round ()
Delattr ()	Hash ()	Memoryview ()	Set ()

Important functions

filter (function, sequence): executes function (item) on item in sequence and returns an iterator that executes a result of true to a filter object. Can be seen as a filter function. "Do not change the original value, only one filter effect"

def fun1 (s):    if s! = ' A ':        return Sret = Filter (fun1, str) print (ret)         # RET is an iterator object <filter objects at 0x00000 00000a4c518>print (List (ret))   # [' B ', ' C ', ' d ']    

Eval: Calculator function "Use within quotation marks" and return the original type of data directly

Print (eval (' 1+2+3+4+5+6+7+8+9+10 '))    # 55

map (function, sequence) : Executes function (item) on item in sequence, and executes the result into a map iterator returning "change element value"

str = [' m ', ' g ', ' f ', ' W ']def fun2 (s):    return s + "Ood" ret = map (fun2, str) print (ret)  # Map Object iterator print (list (r ET)  # [' Mood ', ' good ', ' food ', ' wood ']

Note: map also supports multiple sequence, which requires that the function also supports the corresponding number of parameter inputs:

def add (x, y):    return X+yprint (list (map (add, Range), range (10))) ##[0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

the difference between map and filter:

def f (s):    return s + ' ood ' li = [' f ', ' m ', ' g ', ' H ']print (list (map (f, Li)))             # [' Food ', ' mood ', ' good ', ' hood '], pieced back heavy New Output print (List (filter (F, Li))          # [' F ', ' m ', ' g ', ' h '], output the original value

reduce (function, sequence, starting_value): invokes function for the item order in sequence, and can be called as an initial value if there is a starting_value. "Direct return results, the difference between map and filter, factorial is very convenient"

From Functools import reducedef FAC (x, y):    return x * yprint (Reduce (FAC, range (1, 5))     # 24print (Reduce (FAC, range (1, 5),) # 240getattr (obj, name, default) function: Remove a property or method from the Obj object without printing the default value class Foo:    def __init__ (self, name, Age):        self.name = name        self.age = Ageobj = Foo (' FTL ', +) print (obj.name) b = ' name ' Print (' obj.__dict__[b]: ', obj. __DICT__[B]   # through the Dictionary value print ("GetAttr (obj, ' name '):", GetAttr (obj, ' name ')) # takes the  value setattr (obj, ') through the built-in function getattr School ', ' Xupt ') print (hasattr (obj, ' School ')) print (Delattr (obj, ' School '))   # Other built-in methods that manipulate the members of an object in the form of a string

Learning---python learning with built-in functions