How to convert two-dimensional array to one-dimensional array in php

PHP is a very popular programming language that has powerful functions for processing arrays. In PHP, two-dimensional array is a very common data type, which consists of multiple one-dimensional arrays. When we need to convert a two-dimensional array into a one-dimensional array, we need to use some specific functions and techniques. Below, we will introduce several commonly used methods.

Method 1: Use a foreach loop

The first method is to use a foreach loop to traverse the two-dimensional array and add each element to a new one-dimensional array. The following is a sample code:

$two_dim_array = array(
  array('apple', 'banana', 'cherry'),
  array('dog', 'cat', 'rat'),
  array('red', 'green', 'blue')
);

$one_dim_array = array();
foreach ($two_dim_array as $key => $value) {
  foreach ($value as $k => $v) {
    array_push($one_dim_array, $v);
  }
}
print_r($one_dim_array);

Output result:

Array
(
    [0] => apple
    [1] => banana
    [2] => cherry
    [3] => dog
    [4] => cat
    [5] => rat
    [6] => red
    [7] => green
    [8] => blue
)

Method 2: Use the array_merge() function

The second method is to use the array_merge() function to merge multiple Groups of dimensions are combined into a new one-dimensional array. We can get a new one-dimensional array by looping through the two-dimensional array and merging each one-dimensional array using the array_merge() function. The following is a sample code:

$two_dim_array = array(
  array('apple', 'banana', 'cherry'),
  array('dog', 'cat', 'rat'),
  array('red', 'green', 'blue')
);

$one_dim_array = array();
foreach ($two_dim_array as $key => $value) {
  $one_dim_array = array_merge($one_dim_array, $value);
}
print_r($one_dim_array);

Output result:

Array
(
    [0] => apple
    [1] => banana
    [2] => cherry
    [3] => dog
    [4] => cat
    [5] => rat
    [6] => red
    [7] => green
    [8] => blue
)

Method 3: Use the array_reduce() function

The third method is to use the array_reduce() function to convert the two-dimensional array into Convert to a one-dimensional array. The array_reduce() function accepts an array and a callback function as parameters. The callback function iterates and calculates the values ​​​​in the array one by one, and finally returns a single value. We can use an empty array as the initial value and merge each one-dimensional array into a new one-dimensional array in the callback function. The following is a sample code:

$two_dim_array = array(
  array('apple', 'banana', 'cherry'),
  array('dog', 'cat', 'rat'),
  array('red', 'green', 'blue')
);

$one_dim_array = array_reduce($two_dim_array, function($carry, $item) {
  return array_merge($carry, $item);
}, array());
print_r($one_dim_array);

Output result:

Array
(
    [0] => apple
    [1] => banana
    [2] => cherry
    [3] => dog
    [4] => cat
    [5] => rat
    [6] => red
    [7] => green
    [8] => blue
)

Summary

The above are the three common methods in PHP to convert a two-dimensional array into a one-dimensional array. Using the foreach loop and the array_merge() function both require traversing the array, while using the array_reduce() function can be more concise, but it may confuse some developers. Therefore, in actual development, we can choose the most suitable method according to our needs to improve development efficiency.

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