身份运算符

• is
• is not

如果两个变量取值相等，则返回True

>>> a = 1
>>> b = 1
>>> a is b
True
>>> a == b
True
>>> a = 1
>>> b = 1.0
>>> a is b
False
>>> a == b
True

关系运算符比较的是2个值是否相等。 is 比较的是2个变量的身份（即内存地址）是否相等

>>> a = 1
>>> b = 1
>>> id(a)
4308970144
>>> id(b)
4308970144
>>> c = 1.0
>>> id(c)
140223825357584

>>> a = {1,2,3}
>>> b = {2,1,3}
>>> id(a)
140223825756448
>>> id(b)
140223825757568
>>> a is b
False
>>> a == b
True

>>> c = (1,2,3)
>>> d = (2,1,3)
>>> id(c)
140223825449856
>>> id(d)
140223825451392
>>> c == d
False
>>> c is d
False

>>> c = {1,2,3}
>>> d = {1,2,3}
>>> id(c)
140223825757792
>>> id(d)
140223825758016
>>> c==d
True
>>> c is d
False