Tables and details of built-in functions

1. Built-in function table

Detailed information

2. Built-in function details

2.1 abs(x)

Return absolute value

>>> abs(-5)
5

　

2.2 all(iterable )

If all elements of this iterable are true, return true. It’s true if it’s not 0, it’s true if it’s negative, it’s true if it’s empty

>>> all([-1,2,3,4,5])
True

>>> all((-1,2,3,4))
True

>>> all([])
True

>>> all([-1,0,2,3,4])
False

　

2.3 any(iterable)

If one of the iterable elements is true, it returns true, and an empty list returns false.

>>> any([-1,0,1,2,3])
True
>>> any([])
False
>>> any([0])
False
>>> any([1])
True

　

2.4 ascii(object)

Turn the memory object into a printable String format

>>> ascii([1,2,3,4])
'[1, 2, 3, 4]'

2.5 bin(x)

Convert an integer It is a binary number

>>> bin(11111)
'0b10101101100111'
>>> bin(-1223)
'-0b10011000111'

>>> bin(1.2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: &#39;float&#39; object cannot be interpreted as an integer

　

2.6 boll([X])

is not empty It is true, otherwise it is false; if it is correct, it is true, if it is wrong, it is false

>>> bool([1,2,3,4])
True
>>> bool([])
False
>>> bool("1")
True
>>> bool("sfasfsa")
True
>>> bool("")
False
>>> bool(-1)
True
>>> bool(0)
False
>>> bool()
False
>>> bool({})
False
>>> bool({"sdf":1})
True
>>> bool(())
False
>>> bool((1,2))
True
>>> bool(3>5)
False
>>> bool(3<5)
True

　

2.7 bytearray([source[,encoding[ ,errors]]])

byte array, and binary bytes can be modified

>>> b=bytearray("abcd",encoding="utf-8")
>>> b[0]     # 打印第一个元素的ascii值
97
>>> b[0]=100   # 修改第一个元素的ascii值，赋值只能是ascii值
>>> b
bytearray(b'dbcd')

　

2.8 bytes ([source[, encoding[, errors]]])

Convert string to bytes

>>> b=bytes("abcd",encoding="utf-8")
>>> b
b'abcd'
>>> b[0]
97
>>> b[0]=100
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: &#39;bytes&#39; object does not support item assignment

　

2.9 callable (object)

Determine whether an object can be called. Only if there are parentheses at the end, it means it can be called, such as: function, class

>>> callable([])
False
>>> def bus():pass
...
>>> callable(bus)
True

　

2.10 chr(i)

Find the corresponding character through the ascii value

>>> chr(99)
'c'

2.11 ord(c)

Find the corresponding ascii value based on the character

>>> ord("c")
99

2.12 dict(**kwarg), dict(mapping,**kwarg), dict(iterable, **kwarg)

Generate a dictionary

#传入非固定关键字参数
>>> dict(name="bigberg",age=22)
{'name': 'bigberg', 'age': 22}

# 传入列表
>>> s_list=[("name","bigberg"),("age",22)]
>>> dict(s_list)
{'name': 'bigberg', 'age': 22}

>>> n_list=[['names',['zhangsan','lisi','wangwu']],['job',['doctor','teacher','police']]]
>>> dict(n_list)
{'names': ['zhangsan', 'lisi', 'wangwu'], 'job': ['doctor', 'teacher', 'police']}

　

2.13 dir(object)

View method

dir(list): How to view a list

dir(dict): How to view a dictionary

　

2.14 divmod(a,b)

Floor division, obtain a tuple, the first element of the tuple is the quotient, and the second element is the remainder.

>>> divmod(14,3)
(4, 2)

　

2.15 enumerate(iterable,start=0)

Get a list, each element in the list They are all a tuple. The first number of the tuple is the index of iterable, and the second number is the element of iterable.

fruits = ['apple', 'orange', 'banana']
print(list(enumerate(fruits)))

#输出
[(0, 'apple'), (1, 'orange'), (2, 'banana')]

　

2.16 eval(expression, globals=None, locals=None)

Turn a dictionary type string into a dictionary, turn an integer type character into an int type, or simple conversions such as addition, subtraction, multiplication and division into an expression.

>>> s = "5+989"
>>> eval(s)
994

　

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