Python - Comparison Operators

Python Comparison Operators

Comparison operators in Python are very important inPython's conditional statements (if, else andelif) andlooping statements (while andfor loops). Thecomparison operators also calledrelational operators. Some of the well known operators are "<" stands for less than, and ">" stands for greater than operator.

Python uses two more operators, combining "=" symbol with these two. The "<=" symbol is for less than or equal to operator and the ">=" symbol is for greater than or equal to operator.

Different Comparison Operators in Python

Python has two more comparison operators in the form of "==" and "!=". They are foris equal to andis not equal to operators. Hence, there are six comparison operators in Python and they are listed below in this table:

Comparison operators are binary in nature, requiring two operands. An expression involving a comparison operator is called a Boolean expression, and always returns either True or False.

Example

a=5b=7print (a>b)print (a<b)

It will produce the followingoutput −

FalseTrue

Both the operands may bePython literals,variables or expressions. Since Python supports mixed arithmetic, you can have any number type operands.

Example

The following code demonstrates the use of Python'scomparison operators with integer numbers −

print ("Both operands are integer")a=5b=7print ("a=",a, "b=",b, "a>b is", a>b)print ("a=",a, "b=",b,"a<b is",a<b)print ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

Both operands are integera= 5 b= 7 a>b is Falsea= 5 b= 7 a<b is Truea= 5 b= 7 a==b is Falsea= 5 b= 7 a!=b is True

Comparison of Float Number

In the following example, an integer and a float operand are compared.

Example

print ("comparison of int and float")a=10b=10.0print ("a=",a, "b=",b, "a>b is", a>b)print ("a=",a, "b=",b,"a<b is",a<b)print ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

comparison of int and floata= 10 b= 10.0 a>b is Falsea= 10 b= 10.0 a<b is Falsea= 10 b= 10.0 a==b is Truea= 10 b= 10.0 a!=b is False

Comparison of Complex umbers

Although complex object is a numberdata type in Python, its behavior is different fromothers. Python doesn't support < and > operators, however it does support equality (==)and inequality (!=) operators.

Example

print ("comparison of complex numbers")a=10+1jb=10.-1jprint ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

comparison of complex numbersa= (10+1j) b= (10-1j) a==b is Falsea= (10+1j) b= (10-1j) a!=b is True

You get a TypeError with less than or greater than operators.

Example

print ("comparison of complex numbers")a=10+1jb=10.-1jprint ("a=",a, "b=",b,"a<b is",a<b)print ("a=",a, "b=",b,"a>b is",a>b)

It will produce the followingoutput −

comparison of complex numbersTraceback (most recent call last):  File "C:\Users\mlath\examples\example.py", line 5, in <module>    print ("a=",a, "b=",b,"a<b is",a<b)                                      ^^^TypeError: '<' not supported between instances of 'complex' and'complex

Comparison of Booleans

Boolean objects in Python are really integers: True is 1 and False is 0. In fact, Python treats any non-zero number as True. In Python, comparison of Boolean objects is possible. "False < True" is True!

Example

print ("comparison of Booleans")a=Trueb=Falseprint ("a=",a, "b=",b,"a<b is",a<b)print ("a=",a, "b=",b,"a>b is",a>b)print ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

comparison of Booleansa= True b= False a<b is Falsea= True b= False a>b is Truea= True b= False a==b is Falsea= True b= False a!=b is True

Comparison of Sequence Types

In Python, comparison of only similar sequence objects can be performed. A string object is comparable with another string only. Alist cannot be compared with atuple, even if both have same items.

Example

print ("comparison of different sequence types")a=(1,2,3)b=[1,2,3]print ("a=",a, "b=",b,"a<b is",a<b)

It will produce the followingoutput −

comparison of different sequence typesTraceback (most recent call last):  File "C:\Users\mlath\examples\example.py", line 5, in <module>    print ("a=",a, "b=",b,"a<b is",a<b)                                       ^^^TypeError: '<' not supported between instances of 'tuple' and 'list'

Sequence objects are compared by lexicographical ordering mechanism. The comparison starts from item at 0th index. If they are equal, comparison moves to next index till the items at certain index happen to be not equal, or one of the sequences is exhausted. If one sequence is an initial sub-sequence of the other, the shorter sequence is the smaller (lesser) one.

Which of the operands is greater depends on the difference in values of items at the index where they are unequal. For example, 'BAT'>'BAR' is True, as T comes after R in Unicode order.

If all items of two sequences compare equal, the sequences are considered equal.

Example

print ("comparison of strings")a='BAT'b='BALL'print ("a=",a, "b=",b,"a<b is",a<b)print ("a=",a, "b=",b,"a>b is",a>b)print ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

comparison of stringsa= BAT b= BALL a<b is Falsea= BAT b= BALL a>b is Truea= BAT b= BALL a==b is Falsea= BAT b= BALL a!=b is True

In the following example, two tuple objects are compared −

Example

print ("comparison of tuples")a=(1,2,4)b=(1,2,3)print ("a=",a, "b=",b,"a<b is",a<b)print ("a=",a, "b=",b,"a>b is",a>b)print ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

a= (1, 2, 4) b= (1, 2, 3) a<b is Falsea= (1, 2, 4) b= (1, 2, 3) a>b is Truea= (1, 2, 4) b= (1, 2, 3) a==b is Falsea= (1, 2, 4) b= (1, 2, 3) a!=b is True

Comparison of Dictionary Objects

The use of "<" and ">" operators for Python's dictionary is not defined. In case of theseoperands, TypeError: '<' not supported between instances of 'dict' and 'dict' is reported.

Equality comparison checks if the length of both the dict items is same. Length of dictionary is the number of key-value pairs in it.

Python dictionaries are simply compared by length. The dictionary with fewer elements is considered less than a dictionary with more elements.

Example

print ("comparison of dictionary objects")a={1:1,2:2}b={2:2, 1:1, 3:3}print ("a=",a, "b=",b,"a==b is",a==b)print ("a=",a, "b=",b,"a!=b is",a!=b)

It will produce the followingoutput −

comparison of dictionary objectsa= {1: 1, 2: 2} b= {2: 2, 1: 1, 3: 3} a==b is Falsea= {1: 1, 2: 2} b= {2: 2, 1: 1, 3: 3} a!=b is True