下表列出了所有Python語言支持的標識運算符。

運算符	描述	示例
is	計算結果為true，如果操作符兩側的變量指向相同的對象，否則為false。	x是y，這裡結果是1，如果id(x)的值為id(y)。
is not	計算結果為false，如果兩側的變量操作符指向相同的對象，否則為true。	x不為y，這裡結果不是1，當id(x)不等於id(y)。

示例：

試試下麵的例子就明白了所有Python編程語言提供的標識運算符：

#!/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"

當執行上麵的程序它會產生以下結果：

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