下表列出了所有Python语言支持的标识运算符。

运算符	描述	示例
is	计算结果为true，如果操作符两侧的变量指向相同的对象，否则为false。	x是y，这里结果是1，如果id(x)的值为id(y)。
is not	计算结果为false，如果两侧的变量操作符指向相同的对象，否则为true。	x不为y，这里结果不是1，当id(x)不等于id(y)。

示例：

试试下面的例子就明白了所有Python编程语言提供的标识运算符：

#!/usr/bin/python

a = 20
b = 20

if ( a is b ):
   print "Line 1 - a and b have same identity"
else:
   print "Line 1 - a and b do not have same identity"

if ( id(a) == id(b) ):
   print "Line 2 - a and b have same identity"
else:
   print "Line 2 - a and b do not have same identity"

b = 30
if ( a is b ):
   print "Line 3 - a and b have same identity"
else:
   print "Line 3 - a and b do not have same identity"

if ( a is not b ):
   print "Line 4 - a and b do not have same identity"
else:
   print "Line 4 - a and b have same identity"

当执行上面的程序它会产生以下结果：

Line 1 - a and b have same identity
Line 2 - a and b have same identity
Line 3 - a and b do not have same identity
Line 4 - a and b do not have same identity