Data Projection Techniques in PHP

Welcome! Today, we'll explore Data Projection Techniques in PHP. Data projection allows you to transform data streams by applying specific functions, much like shining a beam of light to reveal the true brilliance of gems amidst a pile.

This lesson will introduce you to data projection using PHP's versatile functions and classes, enabling you to effectively reshape and analyze data streams. Let's dive in!

Data projection involves applying a function to elements of a data stream to create a transformed view. A typical example is selecting specific fields from data arrays.

In PHP, data projection is performed using the array_map function. Here's how you can find the square of each number in a data array:

<?php

// Function to get a number's square
function square($n) {
    return $n * $n;
}

$numbers = [1, 2, 3, 4, 5];  // our data stream

// array_map applies the square function to each number in the array
$squared_numbers = array_map('square', $numbers);

// Print squared numbers
foreach ($squared_numbers as $n) {
    echo $n . " ";
}
// Output: 1 4 9 16 25

?>

For more complex operations on data streams, PHP uses closures (or anonymous functions). Here's how you can convert an array of sentences to lowercase:

<?php

// Array of uppercase sentences
$sentences = ["HELLO WORLD", "PHP IS FUN", "I LIKE PROGRAMMING"];  // our data stream

// array_map applies an anonymous function to each sentence in the array
$lower_sentences = array_map(function($s) {
    return strtolower($s);
}, $sentences);

// Print lowercased sentences
foreach ($lower_sentences as $sentence) {
    echo $sentence . "\n";
}
// Output: hello world
//         php is fun
//         i like programming

?>