In Python, None evaluates to less than zero?
Question:
In Python, None evaluates to less than zero?
ActivePython 2.7.2.5 (ActiveState Software Inc.) based on
Python 2.7.2 (default, Jun 24 2011, 12:21:10) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> None < 0
True
>>> None == 0
False
>>> None > 0
False
>>>
Is this expected?
I would have guessed that None would either be equal to zero (through type coercion), or that all of these statements would return False.
Answers:
It is intentional to make operations like sorting and dictionary comparison well defined.
[citing from the Language Reference]
The operators <, >, ==, >=, <=, and != compare the values of two
objects. The objects need not have the same type. If both are numbers,
they are converted to a common type. Otherwise, objects of different
types always compare unequal, and are ordered consistently but
arbitrary.
See the manual:
Objects of different types, except different numeric types and different string types, never compare equal; such objects are ordered consistently but arbitrarily (so that sorting a heterogeneous array yields a consistent result).
and
CPython implementation detail: 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.
From the docs:
CPython implementation detail: 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.
NoneType compares as smaller than int since the comparison appears to be case-sensitive.
>>> type(0)
<type 'int'>
>>> type(None)
<type 'NoneType'>
>>> 'NoneType' < 'int'
True
In Python, None evaluates to less than zero?
ActivePython 2.7.2.5 (ActiveState Software Inc.) based on
Python 2.7.2 (default, Jun 24 2011, 12:21:10) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> None < 0
True
>>> None == 0
False
>>> None > 0
False
>>>
Is this expected?
I would have guessed that None would either be equal to zero (through type coercion), or that all of these statements would return False.
It is intentional to make operations like sorting and dictionary comparison well defined.
[citing from the Language Reference]
The operators <, >, ==, >=, <=, and != compare the values of two
objects. The objects need not have the same type. If both are numbers,
they are converted to a common type. Otherwise, objects of different
types always compare unequal, and are ordered consistently but
arbitrary.
See the manual:
Objects of different types, except different numeric types and different string types, never compare equal; such objects are ordered consistently but arbitrarily (so that sorting a heterogeneous array yields a consistent result).
and
CPython implementation detail: 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.
From the docs:
CPython implementation detail: 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.
NoneType compares as smaller than int since the comparison appears to be case-sensitive.
>>> type(0)
<type 'int'>
>>> type(None)
<type 'NoneType'>
>>> 'NoneType' < 'int'
True