python 基础 内置函数

Posted 2020-10-17 minger_lcm

 

内置参数

print(all([5,-1,5]))  # 非0都是真 true
print(all([0,-1,5]))  # false

print(any([1,0,5]))  # 有一个数据为真，就为真
print(any([]))       # false

# 把数字转换成二进制
print(bin(1))
‘‘‘
>>> bin(1)
‘0b1‘
>>> bin(2)
‘0b10‘
>>> bin(16)
‘0b10000‘
>>> bin(255)
‘0b11111111‘
>>>
‘‘‘


‘‘‘
# 判断真假
>>> bool(1)
True
>>> bool(0)
False
>>> bool(5)
True
>>> bool([])
False
>>> bool({})
False
>>> bool({1})
True
>>> bool([241])
True
‘‘‘

‘‘‘
a = bytes("abcd",encoding="utf8")
print(a.capitalize(),a)

b = bytearray("abcd",encoding="utf8")
print(b[1])  # 打印ascii
b[1]= 50
print(b)
‘‘‘


# 判断一个事情可否调用 可调用true 不可调用false
print(callable([]))
False


def abc1():pass
print(callable(abc1) )

True

‘‘‘
# ascii数字对应字符串转换
>>>
>>>
>>> chr(97)
‘a‘
>>> chr(98)
‘b‘
>>> chr(90)
‘Z‘
>>> chr(99)
‘c‘
>>>

# 反过来 必须输入ascii字符 转换成数字
>>> ord(‘a‘)
97
>>> ord(‘b‘)
98
>>> ord(‘c‘)
99
>>> ord(‘1‘)
49
>>>
‘‘‘


‘‘‘
# 查看 可以用什么方法
>>> a = []
>>>
>>> dir(a)
[‘__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__‘, ‘__
educe__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__reversed__‘, ‘__rmul__‘, ‘__setattr__
, ‘__setitem__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘append‘, ‘clear‘
 ‘copy‘, ‘count‘, ‘extend‘, ‘index‘, ‘insert‘, ‘pop‘, ‘remove‘, ‘reverse‘, ‘sor
‘]
>>>

‘‘‘

‘‘‘
可以把 字符串转换成原来的数据类型  例如：原来是 list ，dict
eval()

‘‘‘

‘‘‘
# exec函数主要用于执行语句块

>>> exec(‘a=1+3*2*2‘)
>>> exec
<built-in function exec>
>>> a
13
>>>

‘‘‘

 

def abc1(n):
    print(n)

abc1(3)

# 传参数
(lambda c:print(c))(110)

abc = lambda c:print(c)
abc(5)
abc = lambda c:10 if c<5 else c
print(abc(3))

print("===========================================")

# filter
# 打印>6的
res = filter(lambda n:n>6,range(10))
for i in res:
    print(i)


print("===========================================")

# map
# 把里面的集合每个数据 拿出来给前面的函数处理 然后用list方式打印出来
res = map(lambda n:n*2,range(10))
for i in res:
    print(i)

0
2
4
6
8
10
12
14
16
18



print("===========================================")
# 累加 reduce
import functools
res = functools.reduce(lambda x,y:x+y,range(1,10))
print(res)

# 累乘
res = functools.reduce(lambda x,y:x*y,range(1,10))
print(res)

print("===========================================")

# 判断变量存在否
# print(globals())

‘‘‘
>>>
>>> hash(1)
1
>>> hash(2)
2
>>> hash("ming")
2265504022069637367
>>>
>>> hash("mike")
-5868197253725756830
>>>

‘‘‘

# 把一个数 转换成16进制
‘‘‘
>>>
>>> hash(1)
1
>>> hash(2)
2
>>> hash("ming")
2265504022069637367
>>>
>>> hash("mike")
-5868197253725756830
>>>
‘‘‘

# 返回多少次幂  例如 pow（x,y） x的y次方
‘‘‘
>>>
>>> pow(3,3)
27
>>> pow(5,2)
25
>>> pow(8,2)
64
>>>

‘‘‘

# 排序 从小到大
a = {6:2,8:0,1:4,-5:6,99:11,4:22}
#print(a)
print(sorted(a))
[-5, 1, 4, 6, 8, 99]

print(sorted(a.items()))    # key排序
[(-5, 6), (1, 4), (4, 22), (6, 2), (8, 0), (99, 11)]

print(sorted(a.items(),key=lambda x:x[1]))    # 按value排序，x代表一个元素

[(8, 0), (6, 2), (1, 4), (-5, 6), (99, 11), (4, 22)]

print("===========================================")

# 把两个列表对应起来 合并

d = [1,2,3,4,5,6]
e = [‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘]

for i in zip(d,e):
    print(i)

(1, ‘a‘)
(2, ‘b‘)
(3, ‘c‘)
(4, ‘d‘)
(5, ‘e‘)
(6, ‘f‘)

print("===========================================")

__import__(‘生成器‘)