Thinking Like a Programmer•Interactive notebook lesson•Free

Python Operators

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Operators are used to perform some operations on say variables, functions or in general python objects.

Arithmetic operators
Assignment operators
Comparison operators
Logical operators
Identity operators
Membership operators
Bitwise operators

Arithmetic Operators

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a = 10
b = 20

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# Addition operator
a + b

Output

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# Substraction operator
a - b

Output

-10

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# Multiplication operator
a * b

Output

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# Division operator
a / b

Output

0.5

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# Modulus operator / remainder operator

3 % 2

Output

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12 % 4

Output

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11 % 4

Output

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a = 10
b = 20
print(a % b)

Output

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# Exponent operator / power operator

2 ** 3    # 2 to the power 3 is 8

Output

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2*2*2

Output

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10 ** 2    # 10 squared

Output

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# Floor division operator
# Returns the integer part of the division without the decimal point

10 // 3

Output

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a // b

Output

Assignment Operators

The = operator

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# The = operator assigns some data to a variable

c = 12
print(c)

Output

Let's increase the value of a variable to understand the next assignment operators

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# Counter intuitive to how we use = sign in our mathematics class
# = sign in python just assigns the right hand side RHS of = sign
# to the left hand side LHS of = sign

d = 5

# we will do d+1 first
# and then assign the increased value to the same variable d

d = d + 1   
print(d)

Output

The += operator

To perform the operation d=d+1 in a pythonic way, we use += operator. Nothing fancy, even I don't use it that often, but other people do use it. So, it becomes important to understand such operators.

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# Initialize the value 9 as variable e

e = 9

# Increase the value of variable e by one
e += 1

print(e)

Output

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f = 10

f += 15   # Again, the same thing as f=f+15

print(f)

Output

The -= operator

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g = 7

g -= 2   # Pythonic way of: g=g-2

print(g)

Output

The *= operator

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h = 5

h *= 2    # Pythonic way of: h=h*2

print(h)

Output

The /= operator

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i = 6

i /= 2    # Pythonic way of: i=i/2

print(i)

Output

3.0

The %= operator

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j = 10

j %= 3    # Pythonic way of: j=j%3, remainder

print(j)

Output

The //= operator

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k = 8

k //= 3    # Pythonic way of: k=k//3, floor division

print(k)

Output

The **= operator

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l = 10

l **= 3    # Pythonic way of: l=l**3

print(l)

Output

So on, we have different assignment operators like: bitwise ones which we will look at later. To be honest, bitwise operators are kind of outside the scope of these basic tutorials, but I'll cover them later on as the reader gets comfortable with the basics first.

Bitwise operators will require us to learn about the binary operations, which might intimidate beginners. But I believe, after building some comfort level bitwise will become really easy to understand.

Comparison Operators

The == operator

Remember the data type boolean, this is where boolean becomes extremely useful.

The == operator compares the RHS right hand side of the == sign to the LHS left hand side of the == sign.

The output is hence returned in True or False depending on if the condition was true or false.

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# Let's compare the integer 4 to the integer 5

# Here we will ask python if the value 4 equals the value 5
# Of course it isn't, that's why python will say False

4 == 5

Output

False

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4 == 4

Output

True

The != operator

This is the not equal operator. It will do something opposite of what == does. It asks python if the LHS is not equal to the RHS.

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4 != 5

Output

True

Yes, 4 does not equal 5, that's why python says yes the condition is true and python returns True.

The > operator

It will check if the LHS is greater than the RHS.

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4 > 1

Output

True

Python says yes LHS is in fact greater than the RHS, so in the above statement python returned True (I agree).

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4 > 8

Output

False

LHS is not greater than the RHS, python does not agree, so, python says False.

The < operator

Should be pretty intuitive by now. This < sign will ask python if the LHS is lesser than the RHS.

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4 < 5

Output

True

Python is happy, python agrees, python says True

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4 < 2

Output

False

Python is not happy, python disagrees, python says False. Python shall not let this mistake pass.

The >= operator

This operator checks if the LHS is greater than or equal to the RHS

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4 >= 4

Output

True

Wow, we finally managed to calm python down. Now, python agrees with the humans, so python says True.

I agree with your conditions, humans!

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4 >= 5

Output

False

The <= operator

This operator checks if the LHS is less than or equal to the RHS

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4 <= 5

Output

True

"haha Tickles I'm impressed"

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6 <= 6

Output

True

"Tickles that was a close call, but I shall allow you for now"

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6 <= 5

Output

False

"Oh boy, you've did it again" with furrows between his eyebrows said Python

Python Logical Operators

The and operator

It compares the LHS of "and" operator to the RHS of the "and" operator and returns True only if both the sides are True, otherwise Python throws a temper tantrum.

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True and True

Output

True

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True and False

Output

False

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False and True

Output

False

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False and False

Output

False

The or operator

The "or" operator checks if any of the LHS or RHS are True.

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True or False

Output

True

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False or True

Output

True

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True or True

Output

True

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False or False

Output

False

The not operator

The "not" operator just reverse the output. If the input is a True, python will lie and say "False". If the input is False, python will smirk and tell the user "True"

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not True

Output

False

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not False

Output

True

Identity Operators

The is operator

Unlike the == operator which checks if two objects of python have same value, the "is" operator checks if two objects are one and the same.

Note: Please pay close attention now

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x = 4
y = 4

x is y

Output

True

At this point you might be willing to think that of course x is same as y as both have the value 4. Lets make a more complicated example.

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x = "random word"

y = "random word"

x is y

Output

False

When our data type is very simple like an integer, python don't create a new object in memory (RAM) for the different objects having same value.

So, when we create the data integer 4 and assign it to variable x, python creates the integer 4 and names it x

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x = 4

Now, if we create another integer 4 and call it y, python will use the integer value 4 that is already stored in python and would give it another name y.

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y = 4

Here, instead of creating a new integer 4, python will re-use the integer 4 from memory and give it another name y. So now, that integer 4 has two names, x and y.

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x is y

Output

True

Python says, x and y are two same objects in memory. Let's look at their memory locations.

id() function

id() function returns the memory location of objects inside python. In simple words, it confirms for us if different variable names are given to just one single object of python.

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id(x)

Output

1982647658896

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id(y)

Output

1982647658896

Things get tricky when our data type is mute-able (We'll talk more about it later)

Let's say we have a sequence data type like a string.

Now, if we create two strings of same value, but use different variable names to reference them, python will give it two different memory locations, so these two string variables now become two different objects in memory.

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string1 = "a "
string2 = "a "

string1 is string2

Output

False

These two sequence data type might have same value but they are stored in different memory locations inside python. So, in this case == operator will say they have same value. The is operator will say they have different memory locations, so they are not the same object.

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string1 == string2

Output

True

The "is not" operator

Just the reverse of "is" keyword as "is not" is associated with the lie ability of python "not" keyword.

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x = 4
y = 4

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x is y

Output

True

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x is not y

Output

False

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string1 = "a "
string2 = "a "

string1 is string2

Output

False

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string1 = "a "
string2 = "a "

string1 is not string2

Output

True

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# Counter intuitive to how we use = sign in our mathematics class # = sign in python just assigns the right hand side RHS of = sign # to the left hand side LHS of = sign d = 5 # we will do d+1 first # and then assign the increased value to the same variable d d = d + 1 print(d)