Python Basics – Boolean Operations

Boolean Operations

Boolean logic consists of operations done between True and False values :

• and ( logical conjunction)
• or ( logical disjunction)
• not ( logical negation )

Object Evaluation

Evaluates as False

• Constants : False and None
• Numeric zero : 0 and 0.0
• Lengths of zero : "" and []

Evaluates as True

• everything else

The AND operator ( and )

It compares 2 operators and if they are true , it evaluates as true   :

• True and True ==> True
• True and False ==> False
• False and False ==> False

The OR operator ( or )

• False or True ==> True
• True or True ==> True
• False or False ==> False

The NOT operator ( not )

It returns the boolean opposite of an item following it

• not True ==> False
• not False ==> True

Order of Operations with NOT

It is lower in order

• True == False ==> False
• not True == False ==> True ( it negates the result of the operation, not the first item )

Object Evaluation

• "CUSIP" and True ==> True
• [] or False ==> False
• not {} ==> True  ( empty dict results in False, but with NOT ==> True

Returning objects

• AND operator  for 2 objects that are both True the last one is returned –> "State" and "Fed" > "State"
• AND operator  for 2 objects where 1st one is False  the first one is returned –> [] and "Fed" > []
• OR operator for 2 objects and 1st one is True, the first one is returned  –> 11 or "account" > 13
• OR operator for 2 objects and 1st one is False, the second one is returned –> 0.0 or {'balance':2200} > {'balance':2200}

Example