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1 Operators in Python

Operators in Python

Python has arithmetic, relational, logical, bit by bit, assignment, membership, and identity operators

Arithmetic operators

Python supplies basic operations with the only additions of the remaining operators, whole quotient and exponentiation

Arithmetic operators
Operator	Operation	Description
+	Addition	Add two operands
–	Subtraction	Subtract the value of the right operand from the left operand Used on a single operand, it changes the sign
*	Multiplication	Multiplication of two operands
/	Division	Divide the operand from the left to the right (the result is always a float)
%	Rest	Gets the rest of dividing the operand on the left by the one on the right
//	Integer quotient	Gets the integer quotient of dividing the operand from the left to the right operand
**	Exponentiation	The result is the left operand raised to the power of the right operand

Note In Python, using the + operator applied to strings concatenates both strings into a single

a = 5
b = 3

sum = a + b #addition example
print(sum) #will return 8

subt = a - b #subtraction example
print(subt) #will return 2

mult = a * b #multiplication example
print(mult) #will return 15

div = a / b #division example
print(div) #will return 1.6667
#Keep in mind that there is no data typing and it will return a float value by default

rest = a % b #rest of division example
print(rest) #will return 2

quot = a // b #integer quotient example
print(quot) #will return 1

expo = a ** b #exponentiation example
print(expo) #will return 125

Relational operators

Are used typically in the conditional expression

The relational operators return boolean values

The operands can be numerical or strings

Relational operators
Operator	Operation	Description
>	Greater than	True if the operand on the left is strictly greater than that on the right False otherwise
<	Less than	True if the operand on the left is strictly less than the one on the right False otherwise
> =	Greater than or equal to	True whether the operand on the left is greater than or equal to that of the right False otherwise
< =	Less than or equal to	True if the operand on the left is less than or equal to that of the right False otherwise
! =	Other than that	True if the operands are different False otherwise
= =	Like	True if the operand on the left is the same as the one on the right False otherwise

Objects of different types, except numeric types, are never compared the same

The operator == it is always defined, but for some types of objects (for example, class objects) it is equivalent to is

Non identical instances of a class are typically compared as non equal unless the class defines the method __eq__()

Instances of a class cannot be sorted with respect to other instances of the same class or other object types, unless the class defines the methods __lt__() and __gt__()

a = 20
b = 30
c = '20'

if a > b:
   print("a is greater than b") #example of major, the types are not taken into account
#in this case it will not show the message for being false
if a > c:
   print("a is greater than c") #example of major, the types are taken into account
#in this case it will not show the message because it is false since it is of different types
if a < b:
   print("a is less than b") #example of minor, types are not taken into account
#in this case it will show the message for being true
if a < c:
   print("a is less than c") #example of minor, it takes into account the types
#in this case it will not show the message because it is false since it is of different types
if a >= b:
   print("a is greater than or equal to b") #example of greater than or equal, the types are not taken into account
#in this case it will not show the message for being false
if a >= c:
   print("a is greater than or equal to c") #example of greater than or equal, the types are taken into account
#in this case it will not show the message because it is false since it is of different types
if a <= b:
   print("a is less than or equal to b") #example of less than or equal, the types are not taken into account
#in this case it will not show the message for being false
if a <= c:
   print("a is less than or equal to c") #example of less than or equal, the types are taken into account
#in this case it will not show the message because it is false since it is of different types
if a != b:
   print("a is different from b") #different example, the types are not taken into account
#in this case it will show the message for being true
if a != c:
   print("a is different from c"); #different example, it takes into account the types
#in this case it will not show the message because it is false since it is of different types
if a == b:
   print("a is the same as b") #example of equal, the types are not taken into account
#in this case it will not show the message for being false
if a == c:
   print("a is the same as c") #example of equal, the types are taken into account
#in this case it will not show the message because it is false since it is of different types

Logical operators

The logical operands is related to the relational as they are normally the operands used are the result of expressions in relational

The resulting values are boolean

Logical operators
Operator	Description
AND	True if both are True
OR	True if one of them is True
NOT	It was True moves on to False and vice versa

a = True
b = False

if a AND b:
    print("a and b are the two true")
else:
    print("a or b are false, or both are false")

if a OR b:
    print("a or b are true, or both are true")
else:
    print("They are both false")

if NOT a:
    print("It was false")
else:
    print("It was true")

Bitwise operators

The way of working of these operators is to convert to the binary operands and then operate with them bitwise

Bitwise operators
Operator	Operation	Description
&	AND	Change the bit to 1 if both were 1
\|	OR	Change the bit to 1 if one of them was 1
^	XOR	Change the bit to 1 if one of them was 1, but not both
~	NOT	Change the bit to 1 if it was 0 Change the bit to 0 if it was 1
<<	Propagation to the left	Shift the value to the left by entering zeros, if it goes out of range, values are lost
>>	Spread to the right	Moves the value to the right entering by the left, the sign bit and eliminating the values that are out by the right

Note Propagation operators take two operands: the first is the variable to propagate and the second is the number of positions to propagate

a = 4 #in binary is 0100
b = 5 #in binary is 0101

c = a & b #AND example
print(c) #will return the value 4 in binary is  0100

c = a | b #OR example
print(c) #will return the value 5 in binary is 0101

c = a ^ b #XOR example
print(c) #will return the value 1 in binary is 0001

c = a << b #left spread example
print(c) #will return the value 128 in binary is ‭1000 0000‬

c = a >> b #right spread example
print(c) #will return the value 0 in binary is 0000

a = ~a #NOT example
print(a) #will return the value -5 in binary is -0101

c = a << b; #propagation to the left of a negative number example
print(c) #will return the value -160 in binary is -0101 0000

c = a >> b; #propagation to the right of a negative number example
print(c) #will return the value -1 in binary is -0001

Assignment operators

The assignment is also an operator that returns the variable modified

The mapping operator in Python is =

The assignment operators shown below are but abbreviations that make expressions more comfortable and simple, even if they are sometimes more unreadable

Assignment operators
Operator	Expression	Equivalence
=	A = B = C D = ‘Text’	A = C B = C D = ‘Text’
+ =	A + = 4	A = A + 4
– =	A – = 3 * B	A = A – (3 * B)
* =	A * = 2	A = A * 2
** =	A ** = 2	A = A ** 2
/ =	A / = 35 + B	A = A / (35 + B)
% =	A % = B	A = A % B
// =	A // = B	A = A // B
>> =	A >> = 1	A = A >> 1
<< =	A << = B	A = A << B
& =	A & = (C + = 3)	C = C +3 A = A & C
^ =	A ^ = 2	A = A ^ 2
\| =	A \| = C	A = A \| C

Membership operators

Membership operators are used to check whether a value or variable is in a sequence (list, tuple, dict, set or str)

Membership operators
Operator	Expression	Equivalence
in	Included	Returns True if the value is in a sequence False otherwise
not in	Not included	Returns True if the value is not in a sequence False otherwise

lists = [1, 3, 2, 7, 9, 8, 6]

if 4 in lists:
    print("4 was on the list")
else:
    print("4 was not on the list")

if 5 not in lists:
    print("5 was not on the list")
else:
    print("5 was on the list")

Identity operators

These operators will be used to check whether or not two variables are the same object

Membership operators
Operator	Expression	Equivalence
is	Equal objects	Returns True if both operands refer to the same object False otherwise
is not	Different objects	Returns True if both operands do not refer to the same object False otherwise

x = 5
lists = [1, 5]

if x is lists:
    print("x same as list") #won't show it because x doesn't have the same reference as lists
else:
    print("x not the same as list") #will show it because x does not have the same reference as lists

if x is not lists[1]:
    print("x not the same as list") #will not display it because x has the same reference as the element contained in lists[1]
else:
    print("x same as list") #will display it because x has the same reference as the element contained in lists[1]

Preference

The operator precedence will determine the order in which they are running in a given expression

Using parentheses will check that the operations are carried out according to us we want to

In Python, the preference for operators from highest to lowest is as follows:

Preference

Parenthesis

(

)

Exponentiation

Unaries

–

Mul / Div / Rest / Div integer

Addition / Subtract

–

Spread

Bit by bit

Relational

< =

> =

Equality

= =

Assignment

+ =

– =

* =

* * =

/ =

// =

% =

& =

| =

^ =

>> =

<< =

Identity

is not

Membership

not in

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Operators in Python

Operators in Python

Arithmetic operators

Relational operators

Logical operators

Bitwise operators

Assignment operators

Membership operators

Identity operators

Preference

Web page of Sergio Cárcamo Garcia dedicated to the computing and related topics such as programming languages, statistics, mathematics, etc

Operators in Python

Arithmetic operators

Relational operators

Logical operators

Bitwise operators

Assignment operators

Membership operators

Identity operators

Preference

Web page of Sergio Cárcamo Garcia dedicated to the computing and related topics such as programming languages, statistics, mathematics, etc

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