Python has more than 60 built-in functions, of which 35 are combed today
1 abs()
Modulus of Absolute or Complex Numbers
.
In [1]: abs(-6)
Out[1]: 6
2 all()
Accepts an iterator and returns True if all elements of the iterator are true or False otherwise
In [2]: all([1,0,3,6])
Out[2]: False
In [3]: all([1,2,3])
Out[3]: True
3 any()
Accepts an iterator that returns True if an element in the iterator is true, or False if it is not
In [4]: any([0,0,0,[]])
Out[4]: False
In [5]: any([0,0,1])
Out[5]: True
4 ascii()
Call the repr() method of the object to get the return value of the method
In [30]: class Student():
...: def __init__(self,id,name):
...: self.id = id
...: self.name = name
...: def __repr__(self):
...: return 'id = '+self.id +', name = '+self.name
In [33]: print(xiaoming)
id = 001, name = xiaoming
In [34]: ascii(xiaoming)
Out[34]: 'id = 001, name = xiaoming'
5 bin()
Convert decimal to binary
In [35]: bin(10)
Out[35]: '0b1010'
6 oct()
Convert decimal to octal
In [36]: oct(9)
Out[36]: '0o11'
7 hex()
Convert decimal to hexadecimal
In [37]: hex(15)
Out[37]: '0xf'
8 bool()
Test whether an object is True or False.
In [38]: bool([0,0,0])
Out[38]: True
In [39]: bool([])
Out[39]: False
In [40]: bool([1,0,1])
Out[40]: True
9 bytes()
Convert a string to a byte type
In [44]: s = "apple"
In [45]: bytes(s,encoding='utf-8')
Out[45]: b'apple'
10 str()
Convert character type, numeric type, etc. to string type
In [46]: integ = 100
In [47]: str(integ)
Out[47]: '100'
11 callable()
To determine whether an object can be called, a callable object, such as a function str, int, and so on, is called. However, the instance of xiaoming in Example 4 is not callable:
In [48]: callable(str)
Out[48]: True
In [49]: callable(int)
Out[49]: True
In [50]: xiaoming
Out[50]: id = 001, name = xiaoming
In [51]: callable(xiaoming)
Out[51]: False
12 chr()
View ASCII characters corresponding to decimal integers
In [54]: chr(65)
Out[54]: 'A'
13 ord()
View a decimal number corresponding to an ascii
In [60]: ord('A')
Out[60]: 65
14 classmethod()
The function corresponding to the classmethod modifier does not require instantiation and the self parameter, but the first parameter needs to be a cls parameter representing its own class, which can be used to call the properties of the class, the methods of the class, the instantiated object, and so on.
In [66]: class Student():
...: def __init__(self,id,name):
...: self.id = id
...: self.name = name
...: def __repr__(self):
...: return 'id = '+self.id +', name = '+self.name
...: @classmethod
...: def f(cls):
...: print(cls)
15 complie()
Compile the string into code python may recognize or execute, or read the text as a string and recompile.
In [74]: s = "print('helloworld')"
In [75]: r = compile(s,"<string>", "exec")
In [76]: r
Out[76]: <code object <module> at 0x0000000005DE75D0, file "<string>", line 1>
In [77]: exec(r)
helloworld
16 complex()
Create a complex number
In [81]: complex(1,2)
Out[81]: (1+2j)
17 delattr()
Delete properties of objects
In [87]: delattr(xiaoming,'id')
In [88]: hasattr(xiaoming,'id')
Out[88]: False
18 dict()
Create a data dictionary
In [92]: dict()
Out[92]: {}
In [93]: dict(a='a',b='b')
Out[93]: {'a': 'a', 'b': 'b'}
In [94]: dict(zip(['a','b'],[1,2]))
Out[94]: {'a': 1, 'b': 2}
In [95]: dict([('a',1),('b',2)])
Out[95]: {'a': 1, 'b': 2}
19 dir()
Returns a list of variables, methods, and defined types in the current range without parameters; returns properties of parameters with parameters, a list of methods.
In [96]: dir(xiaoming)
Out[96]:
['__class__',
'__delattr__',
'__dict__',
'__dir__',
'__doc__',
'__eq__',
'__format__',
'__ge__',
'__getattribute__',
'__gt__',
'__hash__',
'__init__',
'__init_subclass__',
'__le__',
'__lt__',
'__module__',
'__ne__',
'__new__',
'__reduce__',
'__reduce_ex__',
'__repr__',
'__setattr__',
'__sizeof__',
'__str__',
'__subclasshook__',
'__weakref__',
'name']
20 divmod()
Remainder and quotient
In [97]: divmod(10,3)
Out[97]: (3, 1)
21 enumerate()
Returns an enumerable object whose next() method returns a tuple.
In [98]: s = ["a","b","c"]
...: for i ,v in enumerate(s,1):
...: print(i,v)
...:
1 a
2 b
3 c
22 eval()
Evaluates the string str as a valid expression and returns the result of the calculation; takes out the contents of the string
In [99]: s = "1 + 3 +5"
...: eval(s)
...:
Out[99]: 9
23 exec()
Execute string or complie method compiled string, no return value
In [74]: s = "print('helloworld')"
In [75]: r = compile(s,"<string>", "exec")
In [76]: r
Out[76]: <code object <module> at 0x0000000005DE75D0, file "<string>", line 1>
In [77]: exec(r)
helloworld
24 filter()
Filter, construct a sequence, equivalent to
[ item for item in iterables if function(item)]
Setting filter conditions in the function loops through the elements in the iterator one by one, leaving behind the elements when the return value is True to form a filter-type data.
In [101]: fil = filter(lambda x: x>10,[1,11,2,45,7,6,13])
In [102]: list(fil)
Out[102]: [11, 45, 13]
25 float()
Convert a string or integer to a floating point number
In [103]: float(3)
Out[103]: 3.0
26 format()
Formatting the output string, format(value, format_spec) is essentially a call to the format(format_spec) method of value.
In [104]: print("i am {0},age{1}".format("tom",18))
i am tom,age18
27 frozenset()
Create a collection that cannot be modified.
In [105]: frozenset([1,1,3,2,3])
Out[105]: frozenset({1, 2, 3})
28 getattr()
Get the properties of the object
In [106]: getattr(xiaoming,'name')
Out[106]: 'xiaoming'
29 globals()
Returns a dictionary describing the current global variable
30 hasattr()
In [110]: hasattr(xiaoming,'name')
Out[110]: True
In [111]: hasattr(xiaoming,'id')
Out[111]: False
31 hash()
Returns the hash value of an object
In [112]: hash(xiaoming)
Out[112]: 6139638
32 help()
Return help documentation for objects
In [113]: help(xiaoming)
Help on Student in module __main__ object:
class Student(builtins.object)
| Methods defined here:
|
| __init__(self, id, name)
|
| __repr__(self)
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
33 id()
Returns the memory address of the object
In [115]: id(xiaoming)
Out[115]: 98234208
34 input()
Get user input
In [116]: input()
aa
Out[116]: 'aa'
35 int()
Int (x, base =10), X may be a string or a numeric value, converting x to a normal integer.If the parameter is a string, it may contain symbols and decimal points.A long integer is returned if it exceeds the representation range of a normal integer.
In [120]: int('12',16)
Out[120]: 18