6.13. Operator Boolean¶

& - and
| - or
^ - xor
&= - iand
|= - ior
^= - ixor
<< - lshift
>> - rshift
<<= - ilshift
>>= - irshift

6.13.1. About¶

Table 6.10. Boolean Operator Overload¶
Operator	Method
`obj & other`	`obj.__and__(other)`
`obj \| other`	`obj.__or__(other)`
`obj ^ other`	`obj.__xor__(other)`

`obj &= other`	`obj.__iand__(other)`
`obj \|= other`	`obj.__ior__(other)`
`obj ^= other`	`obj.__ixor__(other)`

`obj << other`	`obj.__lshift__(other)`
`obj >> other`	`obj.__rshift__(other)`
`obj <<= other`	`obj.__ilshift__(other)`
`obj >>= other`	`obj.__irshift__(other)`

6.13.2. Example¶

>>> True + True
2

>>> True & True
True

6.13.3. AND - Conjunction¶

& 1 = 1
& 0 = 0
& 1 = 0
& 0 = 0

>>> True & True
True
>>>
>>> True & False
False
>>>
>>> False &  True
False
>>>
>>> False &  False
False

6.13.4. OR - Alternative¶

| 1 = 1
| 0 = 1
| 1 = 1
| 0 = 0

>>> True | True
True
>>>
>>> True | False
True
>>>
>>> False | True
True
>>>
>>> False | False
False

6.13.5. XOR - Exclusive Alternative¶

^ 1 = 0
^ 0 = 1
^ 1 = 1
^ 0 = 0

>>> True ^ True
False
>>>
>>> True ^ False
True
>>>
>>> False ^ True
True
>>>
>>> False ^ False
False

6.13.6. Bool¶

>>> a = True
>>> b = False

>>> a & b
False

>>> a ^ b
True

>>> a | b
True

6.13.7. Set¶

>>> a = {1,2,3}
>>> b = {2,3,4}

>>> a & b
{2, 3}

>>> a ^ b
{1, 4}

>>> a | b
{1, 2, 3, 4}

6.13.8. Dict¶

>>> a = {'commander': 'Melissa Lewis', 'botanist': 'Mark Watney'}
>>> b = {'pilot': 'Rick Martinez', 'chemist': 'Alex Vogel'}

>>> a & b
Traceback (most recent call last):
TypeError: unsupported operand type(s) for &: 'dict' and 'dict'

>>> a ^ b
Traceback (most recent call last):
TypeError: unsupported operand type(s) for ^: 'dict' and 'dict'

>>> a | b  
{'commander': 'Melissa Lewis',
 'botanist': 'Mark Watney',
 'pilot': 'Rick Martinez',
 'chemist': 'Alex Vogel'}

>>> a |= b
>>>
>>> a  
{'commander': 'Melissa Lewis',
 'botanist': 'Mark Watney',
 'pilot': 'Rick Martinez',
 'chemist': 'Alex Vogel'}
>>>
>>> b
{'pilot': 'Rick Martinez', 'chemist': 'Alex Vogel'}

6.13.9. Dictionary Update¶

>>> x = {'a':1, 'b':2, 'c':3}
>>> y = {'d':4, 'e':5}
>>>
>>> x | y
{'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}
>>>
>>> x |= y
>>> x
{'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}

>>> old_crew = {'commander': 'Melissa Lewis',
...             'botanist': 'Mark Watney'}
>>>
>>> new_crew = {'chemist': 'Alex Vogel',
...             'pilot': 'Rick Martinez'}
>>>
>>>
>>> old_crew | new_crew  
{'commander': 'Melissa Lewis',
 'botanist': 'Mark Watney',
 'chemist': 'Alex Vogel',
 'pilot': 'Rick Martinez'}

>>> old_crew
{'commander': 'Melissa Lewis', 'botanist': 'Mark Watney'}
>>>
>>> new_crew
{'chemist': 'Alex Vogel', 'pilot': 'Rick Martinez'}
>>>
>>>
>>> crew = old_crew | new_crew
>>> crew  
{'commander': 'Melissa Lewis',
 'botanist': 'Mark Watney',
 'chemist': 'Alex Vogel',
 'pilot': 'Rick Martinez'}

>>> old_crew |= new_crew
>>> old_crew  
{'commander': 'Melissa Lewis',
 'botanist': 'Mark Watney',
 'chemist': 'Alex Vogel',
 'pilot': 'Rick Martinez'}

>>> class dict:
...     def __or__(self, other):
...         return {**self, **other}
...
...     def __ior__(self, other):
...         self.update(other)
...         return self

6.13.10. Use Case - 0x01¶

XOR as pow
Excel uses ^ to rise number to the power of a second number

>>> from dataclasses import dataclass
>>>
>>>
>>> @dataclass
... class Number:
...     value: int
...
...     def __xor__(self, other):
...         return Number(self.value ** other.value)
>>>
>>>
>>> a = Number(2)
>>> b = Number(4)
>>>
>>> a ^ b
Number(value=16)

6.13.11. Use Case - 0x02¶

Game

>>> hero >> Direction(left=10, up=20)  

6.13.12. Use Case - 0x03¶

Numpy

>>> import numpy as np

>>> a = np.array([[1, 2, 3],
...               [4, 5, 6],
...               [7, 8, 9]])
>>>
>>> a > 2
array([[False, False,  True],
       [ True,  True,  True],
       [ True,  True,  True]])
>>>
>>> (a>2) & (a<7)
array([[False, False,  True],
       [ True,  True,  True],
       [False, False, False]])
>>>
>>> (a>2) & (a<7) | (a>3)
array([[False, False,  True],
       [ True,  True,  True],
       [ True,  True,  True]])

Python understands this:

>>> ~( (a>2) & (a<7) | (a>3) )
array([[ True,  True, False],
       [False, False, False],
       [False, False, False]])

As as chained calls of the following methods:

>>> a.__gt__(2).__and__(a.__lt__(7)).__or__(a.__gt__(3)).__invert__()
array([[ True,  True, False],
       [False, False, False],
       [False, False, False]])

6.13.13. Use Case - 0x05¶

Talk - Sebastiaan Zeeff: Demystifying Python's Internals: Diving into CPython by implementing... https://www.youtube.com/watch?v=HYKGZunmF50
Łukasz Langa - Life Is Better Painted Black, or: How to Stop Worrying and Embrace Auto-Formatting https://www.youtube.com/watch?v=esZLCuWs_2Y
https://docs.influxdata.com/influxdb/v2.0/query-data/get-started/query-influxdb/

>>> def upper(text):
...     return str.upper(text)
>>>
>>> def lower(text):
...     return str.lower(text)
>>>
>>> def capitalize(text):
...     return str.capitalize(text)

Let's make a transformation:

>>> name = 'Mark Watney'
>>> upper(name)
'MARK WATNEY'

What if we have a pipe operator to do that?

>>> name = 'Mark Watney'
>>> name |> upper  
Traceback (most recent call last):
SyntaxError: invalid syntax

Why? Because we can chain multiple pipe operations:

>>> name = 'Mark Watney'
>>> name |> upper |> lower |> capitalize
Traceback (most recent call last):
SyntaxError: invalid syntax