2.1.3 Comparisons

Comparison operations are supported by all objects. 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 and y <= 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).  

This table summarizes the comparison operations:

Operation  Meaning  Notes 
< strictly less than  
<= less than or equal  
> strictly greater than  
>= greater than or equal  
== equal  
!= not equal (1)
<> not equal (1)
is object identity  
is not negated object identity  


<> and != are alternate spellings for the same operator. (I couldn't choose between ABC and C! :-)  != is the preferred spelling; <> is obsolescent.

Objects of different types, except different numeric types, never compare equal; such objects are ordered consistently but arbitrarily (so that sorting a heterogeneous array yields a consistent result). Furthermore, some types (for example, file objects) support only a degenerate notion of comparison where any two objects of that type are unequal. Again, such objects are ordered arbitrarily but consistently.  

Instances of a class normally compare as non-equal unless the class  defines the __cmp__() method. Refer to the Python Reference Manual for information on the use of this method to effect object comparisons.

Implementation note: Objects of different types except numbers are ordered by their type names; objects of the same types that don't support proper comparison are ordered by their address.

Two more operations with the same syntactic priority, "in" and "not in" , are supported only by sequence types (below).

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