Скачать или смотреть How to Randomly Sample an Array without Consecutive Duplicates and the Same nth Elements

Discover how to create a JavaScript function that samples an array while avoiding consecutive duplicates and ensuring that no `n`th elements repeat in their respective positions.
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Random Sampling of Arrays in JavaScript: Avoiding Consecutive Duplicates

Are you looking to create a function in JavaScript that samples an array a specified number of times, while also ensuring that no number appears twice in a row? If so, you're in the right place! This guide will break down how to achieve that through an easy-to-understand explanation and example.

The Problem Statement

In JavaScript, you want a function that:

Randomly samples from an input array arr.

Samples a total of size² elements from this array.

Ensures that no number appears twice in a row.

Ensures that every sizeth item does not repeat the prior sizeth item.

For instance, if you provide the input [1,2,3,4] and size as 2, you’re expecting the output to be an array like [2,4,3,2,4,1, ...] but must not contain any instances like 2,2 or 1,1.

Understanding the Solution

To achieve the sampling while maintaining the constraints mentioned above, we can use functional programming principles along with some clever logic. Let’s break down the solution.

Key Components of the Solution

Random Element Selection:

We begin by creating a function to randomly select an element from the array.

Exclusion of Previous Values:

We create a secondary function that randomly selects an element while excluding the last selected value and, when necessary, the last sizeth selected value.

Iterate to Create the Final Array:

By leveraging array mapping, we iterate the required number of times to fill the final output array while implementing our rules.

Implementation of the Solution

Here is the JavaScript code that implements the above logic:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Random Selection: The rand function generates a random index to access elements of the array.

Excluding Last Values: The randExcept function ensures that the newly selected random value is not present in the excluded array (which holds the last selected element and, if applicable, the last checked sizeth element).

Filling the Array: indexes.map generates the sampling. Depending on the index, it checks for duplicates before assigning a value to the final array.

Finishing Touches

This approach allows you to efficiently sample from an array while maintaining the constraints. It effectively avoids duplicates both in consecutive positions and prevents the repetition of sizeth elements.

Conclusion

By following the breakdown above, you can implement a function that achieves the desired array sampling functionality in JavaScript. Not only have we tackled the problem using functional programming principles, but we've also ensured high readability and maintainability of the code.

Feel free to adapt the code to suit your specific needs, and happy coding!