Python Concept: Boolean

Python boolean is one of python's built in data types. It is used to evaluate expression(s) or in other words represent the truth value of a statement. Python boolean variables is defined by the True or False keywords. Python boolean function is represented by bool().

Most python data types can be evaluated using the boolean function.

Using a bool() on most data type values returns True, except for the number 0, an empty string or list(or set, tuple, dictionary) which returns False. Here are some examples below:

bool(1)
 True
 bool(0)
 False
 bool([2,'j',4.66])
 True

Evaluating expression

You can compare different expression to know the truth statement between the expressions. An example is below:

x=100
 y=100.1
 print(y < x)
 False

Python allows you to the check the data type of an object using the built in function isinstance(), and it returns a boolean value. So if the data type you assigned in arguments of the isinstance() function is accurate, it returns a True value, if not it returns a False value.

isinstance(100.1, int)
 False
 
 isinstance('name', str)
 True

The global function any() also works with booleans. It returns a True if any item in an iterable is true, if not it returns False.

any([2,1,0])
 True
 
 any([0,''])
 False

Booleans in decision making

However booleans can help us in decision making in python. In python decision making (ie if statements), the expression passed to the 'if' statement has to be true before the statements passed to runs or it moves to the next line which is 'else'. You can make adjustments on how you want the decision to be made using booleans.

if (45 <= 39.8) == False:
  print('Yes')
 else:
  print('No')
 
 Yes

Booleans in Functions

Booleans can also be defined in a function to return a boolean as a part of the function. It runs when the function is called.

def function():
  return True
 
 function()
 True