Python Operators.md

#programming #programming/python #semester-1

Arithmetic Operators

Operator	Name
+	Addition
-	Subtraction
*	Multiplication
/	Division
%	Modulus (Remainder)
**	Exponentiation (Power)
//	Floor Division (Round Down)

Assignment Operators

Assigns the value on the right onto the value on the left

Operator	Example	Same As
=	x = 5	x = 5
+=	x +=3	x = x + 3
-=	x -= 3	x = x -3
*=	x *= 3	x = x * 3
/=	x /=3	x = x / 3
%=	x %= 3	x = x % 3
//=	x //= 3	x = x // 3
=	x **= 3	x = x ** 3
&=	x &= 3	x = x & 3
|=	x |= 3	x = x | 3
^=	x ^= 3	x = x ^ 3
>>=	x >>= 3	x = x >> 3
<<=	x <<= 3	x = x << 3
:=	print(x := 3)	x = 3 print(x)

The Walrus Operator

The walrus operator returns and assigns a value to a certain variable. You can use it as an inline assignment shown here:

# Without Walrus
numbers = [2, 8, 0, 1, 1, 9, 7, 7]

num_length = len(numbers)
num_sum = sum(numbers)

description = {
    "length": num_length,
    "sum": num_sum,
    "mean": num_sum / num_length,
}

# With Walrus :=
numbers = [2, 8, 0, 1, 1, 9, 7, 7]

description = {
    "length": (num_length := len(numbers)),
    "sum": (num_sum := sum(numbers)),
    "mean": num_sum / num_length,
}

Both of these code snippets are the same.

Comparison Operators

Comparison Operators return True or False:

Operator	Name
==	Equal To
!=	Not Equal To
>	Greater Than
<	Less Than
>=	Greater Than or Equal To
<=	Less Than or Equal To

Logical Operators

Logical operators are used to combine conditional statements:

Operator	Description
and	Returns True if both statements are True
or	Returns True if one of the statements are true
not	* Reverses the result*

Identity Operators

Identity Operators are used to compare objects, not if they are equal but if they are the same object with the same memory location.

Operator	Description
is	*Returns True if both variables are the same object *
is not	*Returns True if both variables are not the same object *

x = ["apple", "banana"]
y = ["apple", "banana"]
z = x

print(x is z) # True
print(x is y) # False
print(x == y) # True

Membership Operators

Membership operators are used to test if a sequence is presented in an object

Operator	Description
in	*Returns True if a sequence with the specified value is present in the object *
not in	*Returns True if a sequence with the specified value is not present in the object *

fruits = ["apple", "banana", "cherry"]

print("banana" in fruits) # True

text = "Hello World"

print("H" in text) # True
print("hello" in text) # False
print("z" not in text) # True

Bitwise Operators

Operator	Name	Description
&	AND	Sets each bit to 1 if both bits are 1
|	OR	Sets each bit to 1 if one of two bits is 1
^	XOR	Sets each bit to 1 if only one of two bits is 1
~	NOT	* Inverts all the bits*
<<	Zero fill left shift	Shift left by pushing zeros in from the right and let the leftmost bits fall off (e.g. x << 2)
>>	Signed right shift	Shift right by pushing copies of the leftmost bit in from the left, and let the rightmost bits fall off (e.g. x >> 2)

Example

The binary representation of 6 is 0110 The binary representation of 3 is 0011 6 & 3 = 0010 = 2 in decimal

The bin() Function

The bin() function can be used to see the binary form of an integer prefixed with 0b:

x = 6
print(bin(x)) # 0b110 -> String

Order of Operations

The order operators are used in from top to bottom are below:

Operator	Description
()	Parenthesis
**	Exponentiation
+x, -x, ~x	Unary plus, Unary minus, and bitwise NOT
*, /, //, %	Multiplication, Division, Floor Division, and Modulus
+, -	Addition and Subtraction
<<, >>	Bitwise left and right shift
&	Bitwise AND
^	Bitwise XOR
|	Bitwise OR
==, !=, >, >=, <, <=, is, is not, in, not in	Comparisons, Identity and Membership Operators
not	Logical NOT
and	AND
or	OR

The unary plus and minus are when i sign precedes a variable/number such as: -1, -x, +z

If two operators have the same order, then the expression is evaluated from left to right