Python range() Method

range() function in Python is used to generate a sequence of numbers. It is widely used in loops or when creating sequences for iteration.

Let’s look at a simple example of the range() method.

# Generate a sequence of numbers from 0 to 4
for i in range(5):
    print(i)

0
1
2
3
4

Explanation:

• This generates numbers starting from 0 up to 4 (excluding 5) and prints them.

Syntax of range() Method

range(start, stop, step)

Parameters:

• start(optional): The starting value of the sequence. Default is 0.
• stop(required): The ending value of the sequence (exclusive).
• step(optional): The difference between each number in the sequence. Default is 1.

Return Type:

• Returns a range object, which can be converted to a list or used directly in loops.

Examples of range() Method

1. Basic Usage with Default Parameters

When range() function called without arguments defaults to starting at 0 and ending at a specified value (exclusive). It generates a sequence of numbers from 0 to that value.

# Generate numbers from 0 to 4
print(list(range(5)))

[0, 1, 2, 3, 4]

Explanation:

• Starts from 0 by default and ends at 5 (exclusive).

2. Specifying Start and Stop

We can specify both the starting and stopping points of the range. The range(start, stop) generates numbers starting from the start value up to (but not including) the stop value.

# Generate numbers from 2 to 9
print(list(range(2, 10)))

[2, 3, 4, 5, 6, 7, 8, 9]

Explanation:

• Starts from 2 and ends at 10 (exclusive).

3. Using a Step Value

range(start, stop, step) allows us to specify a step value, which controls the difference between consecutive numbers in the range. A positive step generates an increasing sequence, while a negative step generates a decreasing one.

# Generate numbers from 1 to 9 with a step of 2
print(list(range(1, 10, 2)))

[1, 3, 5, 7, 9]

Explanation:

• Numbers are incremented by 2 in each step.

4. Using Negative Steps

By specifying a negative step value, the range() function creates a sequence that decrements from the starting point down to the stopping point, providing reverse order numbers.

# Generate numbers from 10 to 1 in reverse
print(list(range(10, 0, -1)))

[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]

Explanation:

• Useful for iterating backward through a sequence.

Key Characteristics of range()

• Memory Efficiency: range() does not store all values in memory but generates them on demand, making it ideal for large sequences.
• Immutability: A range object cannot be changed after creation.

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Article Tags :

• Python
• python-list
• Python-Built-in-functions
• python-tuple

Practice Tags :

• python
• python-list