如何获得大于一定数值的数组中的最小值？

Question

I have an array like this:

[5229561]=> 8
[5229582]=> 9
[5229583]=> 10
[5229584]=> 11

etc

How can I get the minimum value greater than/equal to 10?

So, it this example, it would give me 5229583. I know about the min() function, but I'm not sure how to get a value greater than 10.

Answer 1

If array is sorted and keys are consecutive(eg 100,101,102 no 78,5,13) you may use binary search.

Overwise you can't do it more quickly than linear search.

Code with O(1) additional memory usage:

$curbest=null;
foreach($data as $k => $v){
    if($v>=10 && (is_null($curbest) || $v<$data[$curbest]))
        $curbest=$k;
}

Answer 2

You need to evaluate the array for this, a number of methods you can use:

for simplicity (and not trying to be fancy) i'll show you the easiest way to learn to do this in PHP.

$input_array = array('5229561' => 8,
                     '5229582' => 9,
                     '5229583' => 10,
                     '5229584' => 11);

foreach ($input_array as $key => $value) {
    if($value >= 10) {
        $output[$key] = $value;
    }
}

$output will be:

array (
      '5229583' => 10,
      '5229584' => 11
      )

hope that helps

EDIT Addition: (Due to RiaD post below) another simple method to do this.

function greaterTen($var) {
    return ($var >= 10);
}

$output = array_filter($input_array,"greaterTen");

and even (as of php5.3):

$output = array_filter($input_array,function ($var) {
    return ($var >= 10);
});

Answer 3

You'd probably want to just sort the array (use ksort if you need the keys to stay the same) and then iterate until you find >= the minimum value.

Like so:

    function findMinValueAbove($array, $min)
    {
      sort($array); # Thanks!
      foreach ($array as $v) if ($v >= $min) return $v;
    }