1. abs() Take the absolute value function

 #!/usr/bin/env python
# _*_ coding: UTF-8 _*_
# Author:taoke
i = 100
print(abs(i))
i = -100
print(abs(i))

2.dict() Create a dictionary

 print(dict({"a":1, "b":2, "c":3}))

3.help() Help function

4.min()  Returns the smallest item iterable Or the smallest two or more parameters .

 print(min([1,2,34,5,6,7,0,100,-2]))

Running results :-2

5.setattr() Assign values to the corresponding properties of an object

setattr(x, 'foobar', 123) Equate to x.foobar = 123

6.all() All for True return True, No one returns Flase

 print(all([1,23,45,3,-1]))
print(all([1,23,45,3,0,-1]))

Running results :

True
False

7.ascii() Change a memory object into a printable string form

8.bin() Convert an integer to a binary string

 print(bin(1))
print(bin(2))
print(bin(3))
print(bin(4))
print(bin(5))
print(bin(255))

Running results :

0b1
0b10
0b11
0b100
0b101
0b11111111

9.dir() When a function has no arguments , Returns the variables in the current range 、 List of types of methods and definitions ; With parameters , Return the properties of the parameter 、 Method list . If the parameter contains a method __dir__(), This method will be called . If the parameter does not contain __dir__(), This method will maximize the collection of parameter information .

 print(dir([1,2,3,4,5]))

Running results :

['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']

10 hex() Convert an integer object to a hexadecimal string representation , Such as 0x The format of .

 #!/usr/bin/env python
# _*_ coding: UTF-8 _*_
# Author:taoke
# Convert an integer to a hexadecimal string
print(12)
print(hex(12))
print(type(hex(12)))
print(hex(-127))

11 next()  Returns the next entry for the iterator

 #!/usr/bin/env python
# _*_ coding: UTF-8 _*_
# Author:taoke
n = iter([i*i for i in range(10)])
#print(type(n))
for i in range(10):
print(next(n))

Running results :

 0
1
4
9
16
25
36
49
64
81

12 slice() Slicing operation

slice[start, stop, step]: Create a slice type . slice(none) It's equivalent to a colon ':'. usage :

s = slice(1,3), a=[1,2,3,4,5,6,7]. be a[s] == a[1:3] == [2, 3]

Multiple axis You just need to slice slice Type variable list Just get up ~: [s1,s2,...]

Can be used to specify axis The section of . For example, requirements a In the axis A slice of an axis , from start To end:

slc = [slice(None)]*len(a.shape)

slc[axis] = slice(start,end)

a[slc] That is .

13 any(): Returns... When an empty iteratable object is passed in False, When any of the iteratable objects is not False, Then return to True

 print(any([0,1,2,3,4]))
print(any(''))
# One of the iteratable objects is True
print(any([1,'']))
print(any(''+''))
# None of the iteratable objects is True
print(any([0,'']))
print(any(''+''))

Running results :

True
True
True
True
False
False

14 divmod():divmod(a,b) Realization a Divide b, Then return the tuple of quotient and remainder . If two parameters a,b Are integers. , So we'll use integer division , The result is equivalent to (a//b, a % b). If a or b Is a floating point number , amount to (math.floor(a/b), a%b).

 print(divmod(100,20))
print(divmod(100.12,20))

Running results :

(5, 0)
(5.0, 0.12000000000000455)

15 id() Get memory address

 vir1 = 1232
vir2 = 1232
vir3 = 22222
print(id(vir1))
print(id(vir2))
print(id(vir3))

Running results :

44024352
44024352
44024368

16 object()

Official documents :

Return a new featureless object. object is a base for all classes. It has the methods that are common to all instances of Python classes. This function does not accept any arguments.

Note:object does not have a __dict__, so you can’t assign arbitrary attributes to an instance of the object class.

translate :

Returns a new featureless object . Objects are the foundation of all classes . It has all the Python Class instances are common methods . This function takes no arguments .

Be careful : Objects have no __dict__, So you can't assign any attribute to an instance of an object class .

17 sorted()

sorted(iterable, cmp=None, key=None, reverse=False) --> new sorted list

The first parameter is the iteratable object , The following parameters have default values , The main points are as follows :

1、cmp, The function of comparison , This has two parameters , The values of the parameters are taken from the iteratable objects , The rule that this function must follow is , Greater than returns 1, Less than returns -1, Is equal to returns 0

2、key, It's basically a comparison element , There is only one parameter , The parameters of the specific function are taken from the iterable object , Specifies an element in an iterable object to sort

3、reverse, Whether to reverse , Not reversed by default

 def cmp_value(x,y):
if x > y :
return 1
elif x < y:
return -1
else:
return 0
so = sorted('this is a string'.split(' '),cmp=cmp_value)
print so

Running results :

['a', 'is', 'string', 'this']

18 ascii()  Returns a printable string representation of an object . When it comes to non ASCII Code time , Will be output \x,\u or \U And so on .

a = ascii(object)
print(a)
print(type(a))

Running results :

<class 'object'>
<class 'str'>

19 enumerate()  Function is used to traverse a data object ( As listing 、 Tuples or strings ) Combined into an index sequence , List both data and data index , Generally used in for Cycle of .

 list1 = [1,2,3,4,5,6]
for i,j in enumerate(list1):
print(i,j)

20 input()  To get input from the console .

 name = input(" Please enter a name :")
print(" name :%s "%name)

Running results :

Please enter a name :taoke
name :taoke

21 oct()  Function to convert an integer to 8 Base string .

 t = oct(123)
print(type(t))
print(t)

Running results :

<class 'str'>
0o173

22 staticmethod()  Returns a static function object , Mainly used as static function modifiers . The feature of static functions is that they can be accessed directly through the class namespace , That is to say, you can use this function without defining class instances ; It can also be accessed through class instances . This one JAVA or C++ The static functions in are the same .

 class testclass(object):
@staticmethod
def func1(a,b):
print(a , b) testclass.func1(1,2)

Running results :

1 2

23 bin()  Convert an integer x Is a binary string representation . If parameters x Not an integer object , It can be overloaded __index__() Function to return an integer .

 print(type(bin(123)))
print(bin(123))

Running results :

<class 'str'>
0b1111011

24 eval()  The string str Evaluate as a valid expression and return the result

 str = input(" Please enter :")
obj = eval(str)
print(obj)

Running results :

Please enter :1+2+3+4
10

25 int()  Function is used to convert a string to an integer

 print(int(1.23))
print(int(0x123))
print(int('',10))
print(int('',16))
print(int('',8))

Running results ;

1
291
123
291
83

26 open()  Function to open a file , Create a  file  object , Related methods can be called to read and write .

27 str() Function converts an object into a human readable form .

28 bool() function

 # Integers 0, Floating point numbers 0.0, An empty list , An empty tuple , An empty dictionary , An empty string , Are all False
print bool(0.0),bool(0),bool([]),bool(()),bool({}),bool('')
# Positive numbers , Negative numbers are True
print bool(8),bool(-3),bool(-3.9),bool(9.8)
# Non empty list , Nonempty tuples , Non empty dictionary , All non empty strings are True
print bool([2,3]),bool((3,4)),bool({'name':'song'}),bool('python')

Running results :

False False False False False False
True True True True
True True True True

10 getattr() 、hasattr()、getattr() and delattr()

setattr(): Set a method or property of an object 
getattr(): Using a method or property of an object
hasattr(): Determine whether an object has a method or property
delattr(): Delete a method or property of an object

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