Question 40182 in PHP Question posted in
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Reduce an array in PHP to get the lowest value

Supposing I have this array in PHP:

Array
(
    [0] => Array
        (
            [color] => Yellow
            [name] => Banana
            [quantity] => 124
        )
    [1] => Array
        (
            [color] => Red
            [name] => Cherry
            [quantity] => 24
        )
    [2] => Array
        (
            [color] => Yellow
            [name] => Apple
            [quantity] => 224
        )

)

How can I reduce this array if :

  • color is yellow and
  • quantity is the lowest

So from the example above, I should have only this array:

Array
(
    [0] => Array
        (
            [color] => Yellow
            [name] => Banana
            [quantity] => 124
        )    
)

What I have tried so far:

$min = array_reduce($array, function($min, $details) {
  return min($min, $details['quantity']);
}, PHP_INT_MAX);

Thanks for any help.

Tags:

3

Answers


  1. 0

    I would just use a simple loop like this, because it’s readable and easy to understand what is happening.

    foreach($array as $arr) {
    if($arr['color'] == 'Yellow') {
        if(!isset($min) || $min['quantity'] > $arr['quantity']) {
            $min = $arr;
        }   
    }
}

print_r($min);

    Output

    Array
(
    [color] => Yellow
    [name] => Banana
    [quantity] => 124
)

    If you want $min to still be an array like your example output, you can just add it to an array like this.

    if(isset($min)) $min = [$min];

    Output

    Array
(
    [0] => Array
        (
            [color] => Yellow
            [name] => Banana
            [quantity] => 124
        )

)
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  2. 0

    A possible solution.

    This solution takes into consideration what has already been created by the applicant, completing the code to obtain the required result.

    $filtered = array_filter ($array, fn ($v) =>  $v['color'] == 'Yellow');
$min = array_reduce($filtered, fn ($minVal, $v) => min($minVal, $v['quantity']), PHP_INT_MAX);
$filtered = array_filter ($filtered, fn ($v) => $v['quantity'] == $min);

print_r ($filtered);

    The first array_filter selects all rows that have color = ‘Yellow’, decreasing the dataset to process.

    With array_reduce we find the smallest value of quantity, like @F_M did, but on a smaller dataset.

    Finally with another array_filter we are going to extract the row with the value just found.

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  3. 0

    I tried to make a more versatile, generic function that could be modified to suit other similar scenarios where the input array does not necessarily contain the keys/values cited in the question.

    $src=array(
    array(
        'colour'=>'Red',
        'name'=>'raspberry',
        'qty'=>524
    ),
    array(
        'colour'=>'yellow',
        'name'=>'Banana',
        'qty'=>124
    ),
    array(
        'colour'=>'green',
        'name'=>'gooseberry',
        'qty'=>23
    ),
    array(
        'colour'=>'Red',
        'name'=>'Cherry',
        'qty'=>24
    ),
    array(
        'colour'=>'green',
        'name'=>'cucumber',
        'qty'=>457
    ),
    array(
        'colour'=>'yellow',
        'name'=>'Banana',
        'qty'=>225
    ),
    array(
        'colour'=>'purple',
        'name'=>'Plum',
        'qty'=>40
    ),
    array(
        'colour'=>'Red',
        'name'=>'strawberry',
        'qty'=>1245
    ),
    array(
        'colour'=>'green',
        'name'=>'lime',
        'qty'=>44520
    ),
    array(
        'colour'=>'yellow',
        'name'=>'mango',
        'qty'=>6225
    )
);

# criteria to apply to the filter
$key='colour';
$value='yellow';
$column='qty';
$dir='low';



function filter( $input, $key, $value, $column, $dir='low' ){
    # filter the array by matching desired field to desired value, ignoring case.
    $filtered=array_filter( $input, function( $item ) use( $key, $value ){
        return is_array( $item ) && strtolower( $item[ $key ] )==strtolower( $value );
    });
    
    # determine the sort order for the filtered results.
    $sort=$dir=='low' ? SORT_ASC : SORT_DESC;
    
    # find the columns by which final output is derived.
    $cols=array_column( $filtered, $column );
    
    # sort the columns.
    array_multisort( $cols, $sort, $filtered );
    
    # return the first item from filtered & now sorted data.
    return array_shift( $filtered );
}

# run the filter
$result=filter( $src, $key, $value, $column, $dir );


printf(
    '<pre>%s</pre>', 
    print_r( is_null( $result ) ? 'No results' : $result, true )
);

    The above yields:

    Array
(
    [colour] => yellow
    [name] => Banana
    [qty] => 124
)

    If the criteria change and you need the highest rather than lowest that can be quickly realised by modifying the $dir variable.

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