Convert one-dimensional array to two-dimensional array php

In PHP development, we often need to convert arrays into two-dimensional arrays and one-dimensional arrays. This article will discuss how to convert one-dimensional arrays into two-dimensional arrays.

Basic concepts of one-dimensional arrays and two-dimensional arrays

In PHP, an array is a special variable that can store multiple values. One-dimensional arrays are the simplest array type, in which each element contains only one value. A two-dimensional array is an ordered data collection that contains multiple one-dimensional arrays.

Methods to convert one-dimensional arrays to two-dimensional arrays

In PHP, there are many ways to convert one-dimensional arrays to two-dimensional arrays. Below we introduce some commonly used methods.

Method 1: Use a for loop

The following is an example of converting a one-dimensional array into a two-dimensional array:

<?php
$arr = ['a', 'b', 'c', 'd', 'e', 'f'];
$rows = 2;
$cols = 3;

$index = 0;
for ($i = 0; $i < $rows; $i++) {
    for ($j = 0; $j < $cols; $j++) {
        if (isset($arr[$index])) {
            $result[$i][$j] = $arr[$index];
            $index++;
        } else {
            break;
        }
    }
}
print_r($result);
?>

In the code, $arr is the one that needs to be converted. Dimensional array, $rows and $cols represent the number of rows and columns of the two-dimensional array respectively. In the loop, we assign the elements in the one-dimensional array to the two-dimensional array by judging the array subscript. The final output is the converted two-dimensional array.

Method 2: Use array_chunk function

PHP built-in function array_chunk can split a one-dimensional array into multiple array blocks, and then return a new array composed of these blocks. We can use this function to convert a one-dimensional array into a two-dimensional array. The sample code is as follows:

<?php
$arr = ['a', 'b', 'c', 'd', 'e', 'f'];
$cols = 3;

$result = array_chunk($arr, $cols);
print_r($result);
?>

In the code, $arr is the one-dimensional array that needs to be converted, and $cols is the length of each two-dimensional array. Use the array_chunk function to convert a one-dimensional array into a two-dimensional array and output the converted result.

Method 3: Use foreach loop

Another way to convert a one-dimensional array into a two-dimensional array is to use PHP's foreach loop. An example is as follows:

<?php
$arr = ['a', 'b', 'c', 'd', 'e', 'f'];
$rows = 2;
$cols = 3;

$index = 0;
foreach (range(1, $rows) as $i) {
    foreach (range(1, $cols) as $j) {
        if (isset($arr[$index])) {
            $result[$i][$j] = $arr[$index];
            $index++;
        } else {
            break;
        }
    }
}
print_r($result);
?>

In the code, we create an array through the range function to represent the number of rows and columns. Then, we assign the value of the one-dimensional array to the two-dimensional array by judging the subscript in the foreach loop. The final output is the converted two-dimensional array.

Method 4: Use array_chunk and array_pad functions

Another method of using array_chunk and array_pad functions to convert a one-dimensional array into a two-dimensional array is as follows:

<?php
$arr = ['a', 'b', 'c', 'd', 'e', 'f'];
$cols = 3;

$result = array_chunk($arr, $cols);
$last = count($result[count($result) - 1]);
if ($last < $cols) {
    $result[count($result) - 1] = array_pad($result[count($result) - 1], $cols, "");
}
print_r($result);
?>

In the code, We first use the array_chunk function to split the one-dimensional array into multiple array blocks, and then use the array_pad function to fill the last array block with null values. This achieves the conversion of a one-dimensional array into a two-dimensional array.

Summary

This article introduces four methods of converting one-dimensional arrays into two-dimensional arrays. In actual development, we can choose the appropriate method to use according to specific needs. No matter which method, we can achieve array conversion through loops, built-in functions, etc.

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