Python3 operator Module

In Python 2.x, the cmp() function was used to compare the size relationship of two lists, numbers, or strings.

In Python 3.X, the cmp() function no longer exists. If you need to implement comparison functionality, you need to import the operator module, suitable for any object, with the following methods:

Methods Included in the operator Module

operator.lt(a, b)
operator.le(a, b)
operator.eq(a, b)
operator.ne(a, b)
operator.ge(a, b)
operator.gt(a, b)
operator.__lt__(a, b)
operator.__le__(a, b)
operator.__eq__(a, b)
operator.__ne__(a, b)
operator.__ge__(a, b)
operator.__gt__(a, b)

operator.lt(a, b) is the same as a < b, operator.le(a, b) is the same as a <= b, operator.eq(a, b) is the same as a == b, operator.ne(a, b) is the same as a != b, operator.gt(a, b) is the same as a > b, operator.ge(a, b) is the same as a >= b.

Example

# Import the operator module
import operator
  
# Numbers
x = 10
y = 20

print("x:",x, ", y:",y)
print("operator.lt(x,y): ", operator.lt(x,y))
print("operator.gt(y,x): ", operator.gt(y,x))
print("operator.eq(x,x): ", operator.eq(x,x))
print("operator.ne(y,y): ", operator.ne(y,y))
print("operator.le(x,y): ", operator.le(x,y))
print("operator.ge(y,x): ", operator.ge(y,x))
print()

# Strings
x = "Google"
y = "Runoob"

print("x:",x, ", y:",y)
print("operator.lt(x,y): ", operator.lt(x,y))
print("operator.gt(y,x): ", operator.gt(y,x))
print("operator.eq(x,x): ", operator.eq(x,x))
print("operator.ne(y,y): ", operator.ne(y,y))
print("operator.le(x,y): ", operator.le(x,y))
print("operator.ge(y,x): ", operator.ge(y,x))
print()

# Check return value
print("type((operator.lt(x,y)): ", type(operator.lt(x,y)))

The output of the above code is:

x: 10 , y: 20
operator.lt(x,y):  True
operator.gt(y,x):  True
operator.eq(x,x):  True
operator.ne(y,y):  False
operator.le(x,y):  True
operator.ge(y,x):  True

x: Google , y: Runoob
operator.lt(x,y):  True
operator.gt(y,x):  True
operator.eq(x,x):  True
operator.ne(y,y):  False
operator.le(x,y):  True
operator.ge(y,x):  True

Comparing two lists:

Example

# Import the operator module
import operator

a = [1, 2]
b = [2, 3]
c = [2, 3]
print("operator.eq(a,b): ", operator.eq(a,b))
print("operator.eq(c,b): ", operator.eq(c,b))

The output of the above code is:

operator.eq(a,b):  False
operator.eq(c,b):  True

Operator Functions

The operator module provides a set of efficient functions corresponding to Python’s built-in operators. For example, operator.add(x, y) is the same as the expression x+y.

The categories of functions include: object comparison operations, logical operations, mathematical operations, and sequence operations.

Object comparison functions are suitable for all objects, and the function names are named according to their corresponding comparison operators.

Many function names are the same as special method names, just without the double underscores. For backward compatibility, many functions with double underscores are also retained. For clarity, it is recommended to use functions without double underscores.

Example

# Python example
# add(), sub(), mul()
  
# Import the operator module
import operator
  
# Initialize variables
a = 4
  
b = 3
  
# Use add() to add two values
print ("add() result :",end="");
print (operator.add(a, b))
  
# Use sub() to subtract two values
print ("sub() result :",end="");
print (operator.sub(a, b))
  
# Use mul() to multiply two values
print ("mul() result :",end="");
print (operator.mul(a, b))

The output of the above code is:

add() result :7
sub() result :1
mul() result :12

Operation	Syntax	Function
Addition	a + b	add(a, b)
String Concatenation	seq1 + seq2	concat(seq1, seq2)
Containment Test	obj in seq	contains(seq, obj)
Division	a / b	truediv(a, b)
Floor Division	a // b	floordiv(a, b)
Bitwise AND	a & b	and_(a, b)
Bitwise XOR	a ^ b	xor(a, b)
Bitwise NOT	~ a	invert(a)
Bitwise OR	`a	b`
Exponentiation	a ** b	pow(a, b)
Identity	a is b	is_(a, b)
Identity	a is not b	is_not(a, b)
Index Assignment	obj[k] = v	setitem(obj, k, v)
Index Deletion	del obj[k]	delitem(obj, k)
Index Retrieval	obj[k]	getitem(obj, k)
Left Shift	a << b	lshift(a, b)
Modulo	a % b	mod(a, b)
Multiplication	a * b	mul(a, b)
Matrix Multiplication	a @ b	matmul(a, b)
Negation (Arithmetic)	- a	neg(a)
Negation (Logical)	not a	not_(a)
Positive	+ a	pos(a)
Right Shift	a >> b	rshift(a, b)
Slice Assignment	seq[i:j] = values	setitem(seq, slice(i, j), values)
Slice Deletion	del seq[i:j]	delitem(seq, slice(i, j))
Slice Retrieval	seq[i:j]	getitem(seq, slice(i, j))
String Formatting	s % obj	mod(s, obj)
Subtraction	a - b	sub(a, b)
Truth Test	obj	truth(obj)
Comparison	a < b	lt(a, b)
Comparison	a <= b	le(a, b)
Equality	a == b	eq(a, b)
Inequality	a != b	ne(a, b)
Comparison	a >= b	ge(a, b)
Comparison	a > b	gt(a, b)