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# Python randrange() Function The `randrange()` method returns a randomly selected element from the range created by the specified start, stop, and step arguments. It is a highly efficient way to generate random integers within a specific sequence or interval. --- ## Description The `randrange()` method selects a random number from a range of values generated by a specified increment (step). By default, the starting value is `0` and the step increment is `1`. This method is part of Python's built-in `random` module. To use it, you must first import the `random` module and call the method using the `random` namespace. --- ## Syntax The syntax for the `randrange()` method is as follows: ```python import random random.randrange([start,] stop [,step]) ``` > **Note:** You cannot access `randrange()` directly. You must import the `random` module and call the method using `random.randrange()`. --- ## Parameters * **`start`** *(Optional)*: The starting value of the range (inclusive). Defaults to `0` if omitted. * **`stop`** *(Required)*: The ending value of the range (exclusive). The generated random number will always be strictly less than this value (`number < stop`). * **`step`** *(Optional)*: The increment/spacing between numbers in the sequence. Defaults to `1` if omitted. --- ## Return Value This method returns a randomly selected integer from the specified range. --- ## Code Examples ### Example 1: Basic Usage with Different Step Values The following example demonstrates how to generate random numbers within a specific range using different step increments. ```python #!/usr/bin/python3 import random # Generate a random even number between 100 and 998 (100 <= number < 1000, step 2) print("randrange(100, 1000, 2) : ", random.randrange(100, 1000, 2)) # Generate a random number from the sequence 100, 103, 106, ..., 997 (100 <= number < 1000, step 3) print("randrange(100, 1000, 3) : ", random.randrange(100, 1000, 3)) ``` **Possible Output:** ```text randrange(100, 1000, 2) : 976 randrange(100, 1000, 3) : 520 ``` --- ### Example 2: Using Single Argument (Stop Only) If you provide only a single argument, it is treated as the `stop` value. The range will start from `0` with a default step of `1`. ```python import random # Generate a random integer from 0 to 9 (0 <= number < 10) num = random.randrange(10) print("Random number from 0 to 9:", num) ``` --- ## Considerations & Best Practices ### 1. `randrange()` vs `randint()` While both functions generate random integers, they have a key difference in how they handle the upper bound: * `random.randrange(start, stop)` is **exclusive** of the `stop` value (similar to Python's `range()` function). * `random.randint(start, stop)` is **inclusive** of the `stop` value. It is equivalent to `random.randrange(start, stop + 1)`. ### 2. ValueError Exceptions A `ValueError` will be raised in the following scenarios: * If the `step` argument is set to `0`. * If you pass non-integer arguments (e.g., floats) to the function. * If the range is empty (e.g., `start` is greater than `stop` while `step` is positive).