How to Randomly Display Elements without Repeating them in a List?

Generating Unique Random Listings without Repeats

Randomizing elements without repetition is a common problem in programming. As you've encountered, using a simple rand() function may not suffice for your specific scenario, where you need to display all elements once before repeats occur.

The most effective method for this problem is to generate a list of all possible numbers, shuffle them to randomize the order, and then use these numbers to retrieve the desired listings. Here's an optimized solution:

<code class="php">$numbers = range(0, 19);
shuffle($numbers);</code>

This code creates an array containing the numbers from 0 to 19 and shuffles them to obtain a random order. You can then iterate through the numbers array and retrieve the corresponding listing from your $businesses array. By using this approach, all 20 listings will be shown once before any are repeated.

An alternative is to use a custom function:

<code class="php">function randomGen($min, $max, $quantity) {
    $numbers = range($min, $max);
    shuffle($numbers);
    return array_slice($numbers, 0, $quantity);
}</code>

This function takes three parameters: the minimum and maximum values, and the desired quantity of random numbers. It generates an array of random numbers within the given range and returns the specified number of elements.

In your case, you can generate 20 unique random numbers within the range of Yelp listings:

<code class="php">print_r(randomGen(0, 20, 20)); // generates 20 unique random numbers</code>

To integrate these techniques with your Yelp API response, you can implement the following update:

1. Generate a random listing ID using one of the proposed methods and store it in your database.
2. On each page refresh, generate a random listing ID and check if it matches the value in your database.
3. If the IDs do not match, display the listing and add the new ID to your database.
4. Repeat steps 1-3 until all 20 listings have been displayed.

By implementing this approach, you will ensure that all 20 listings are shown once before any repeats occur, fulfilling your desired functionality.

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