Python — Operators

Python Operators

Operators are used to perform operations on variables and values.

Here, in the example below, we use the + operator to add (sum) together two values:

print(2 + 3) # 5

Python divides the operators in the following groups:

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

Python Comparison Operators

Comparison operators are used to compare two values:

Table showing Python comparison operators

Python Logical Operators

Logical operators are used to combine conditional statements:

Table showing Python logical operators

Python Identity Operators

Identity operators are used to compare the objects, not if they are equal, but if they are actually the same object, with the same memory location:

Table showing Python identity operators

Python Membership Operators

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

Table showing Python membership operators

Python Bitwise Operators

Bitwise operators are used to compare (binary) numbers:

Table showing Python bitwise operators

Operator Precedence

Operator precedence describes the order in which operations are performed.

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PEMDAS is the operator precedence rule in Python, helping us remember the order of operations to be performed. The PEMDAS rule stands for Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction.

Here’s an example to demonstrate this rule:

operation = (8 * 4 + 7 - 6 / 2)**3 - (3 ** 2 + 2 * 5)
print(operation) # 46637.0

As you can see, this operation gives us as output 46337. To know why, let’s break this down using the PEMDAS rule.

Parentheses

First, we solve the operations inside the parentheses: (8 * 4 + 7 - 6 / 2) and (3² + 2 * 5).

For the first parentheses:

1. Multiplication and Division first: 8 * 4 = 32 and 6 / 2= 3.
2. Then Addition and Subtraction: 32 + 7 - 3 = 36.

For the second parentheses:

1. Exponents first: 3² = 9.
2. Then Multiplication: 2 * 5 = 10.
3. Then Addition: 9 + 10 = 19.

Exponents

Now we apply exponents outside the parentheses: 36³ = 46656.

Subtraction

Finally, subtract the results of the parentheses: 46656–19 = 46637.

Therefore, the final result is 46637.0 (Python gives us this result with a decimal point because of the division).

Boy! This blog has become an Algebric lesson, rather than a Python lesson!

The precedence order is described in the table below, starting with the highest precedence at the top:

Table showing operators precedence order

If two operators have the same precedence, the expression is evaluated from left to right.