Comparisons
There are eight comparison operations in Python. They all have the same priority (which is higher than that of the Boolean operations). Comparisons can be chained arbitrarily; for example, x < y <= z is equivalent to x < y andy <= z, except that y is evaluated only once (but in both cases z is not evaluated at all when x < y is found to be false).
翻译：比较运算符
Python中有八种比较运算符。它们拥有相同的优先级（它们比bool关系运算符的优先级要高）。比较运算符可以连续的如
链式的进行比较;比如 x<y<=z 等价于 x<y and y <= z,但是y表达式只会进行一次计算（但是，如果x<y的表达式为false
，那么两者都不会计算z的表达式）
下面的表格简单是描述了运算符。
前面省略
is 是否是同一个对象
is not 是否为不同的对象
This table summarizes the comparison operations:
| Operation | Meaning |
|---|---|
< |
strictly less than |
<= |
less than or equal |
> |
strictly greater than |
>= |
greater than or equal |
== |
equal |
!= |
not equal |
is |
object identity |
is not |
negated object identity |
Objects of different types, except different numeric types, never compare equal. Furthermore, some types (for example, function objects) support only a degenerate notion of comparison where any two objects of that type are unequal. The <, <=, > and >= operators will raise a TypeError exception when comparing a complex number with another built-in numeric type, when the objects are of different types that cannot be compared, or in other cases where there is no defined ordering.
Non-identical instances of a class normally compare as non-equal unless the class defines the __eq__() method.
Instances of a class cannot be ordered with respect to other instances of the same class, or other types of object, unless the class defines enough of the methods __lt__(), __le__(), __gt__(), and __ge__() (in general, __lt__() and __eq__() are sufficient, if you want the conventional meanings of the comparison operators).
The behavior of the is and is not operators cannot be customized; also they can be applied to any two objects and never raise an exception.
Two more operations with the same syntactic priority, in and not in, are supported only by sequence types (below).
a=1
b=2
c=1
print(a is b,a is not b,a is c ,a is not c)
输出
False True True False
除了数字以外的其他对象不会进行比较。除此之外，有些类型（比如：方法对象）只支持一部分的比较，对于比较两个不同类型的对象. 当使用复数与其他数字类型，或当两个不同的类型进行比较，或者没有定义比较规则的时候
在进行> >= < <=比较时会抛出类型异常TypeError。
不同数据类型之间一般不进行比较除非定了__eq__方法。
即使是相同类型的对象，如果没有定义重载对应的方法也不能进行比较。如果想要方便比较的话可以自行定义。
is 和 is not不支持自定义比较，它们支持所有的不同的规则，并且不会抛出异常。
多个操作之间没有优先级的差异。关键字 in 和 not in只适用于序列。