Find key of array based on variable value between array values

Question

I need to find the left-near key of a base array corresponding to a variable value.

Searched value (in this case) is always between 1 and 779

Better with an example:

$fixedArr = [ 0, 5, 8, 20, 40, 60, 90, 135, 780 ];

$search = 42; // $result = $arr[4] -> 4;
$search = 110; // $result = $arr[6] -> 6;

$search = 134; // $result = $arr[6] -> 6;
$search = 135; // $result = $arr[7] -> 7;

I try with a foreach loop but with no luck, any idea?? Thanks

Search... Search... Search... Use [`array_search`](http://php.net/manual/en/function.array-search.php)... — Praveen Kumar Purushothaman, Dec 17 '15 at 16:31
Do you want the nearest key or indexes of the array between which ? — splash58, Dec 17 '15 at 16:38
searched value is always between (in this case) 1 and 779, so no matter :) — Mindexperiment, Dec 17 '15 at 16:51
@Mindexperiment Mine now gives the left, right, and correct value! `:)` — Praveen Kumar Purushothaman, Dec 17 '15 at 16:55
Your could be fine but I don't need an array as a result,just the left-key value. splash58 would be the right and fastest answer — Mindexperiment, Dec 17 '15 at 17:31
$search = 134; // $result = $arr[6] -> 6; ---> How 134 is near to 90. it must be 135. — Monty, Dec 17 '15 at 18:04

score 2 · Accepted Answer · answered Dec 17 '15 at 16:52

2

searched value is always between (in this case) 1 and 779

$fixedArr = [ 0, 5, 8, 20, 40, 60, 90, 135, 780 ];

$search = 42;
for ($i = 0; $i < count($fixedArr); $i++) 
   if ($search < $fixedArr[$i]) break;

echo $i-1;

answered Dec 17 '15 at 16:52

splash58

26,043
3
22
34

this could be the answer but I think the count should be outside the for loop anche the if statement should be $search **>** $fixedArr[$i] . I give a try – Mindexperiment Dec 17 '15 at 17:16
@Mindexperiment Does mine work now? – Praveen Kumar Purushothaman Dec 17 '15 at 17:18
@splash58 if you make the suggested changes your's would be the answer – Mindexperiment Dec 17 '15 at 17:33
@Mindexperiment why do you think so? – splash58 Dec 17 '15 at 17:43
I'm sorry, only a note for the count outside the loop that is faster, the **<** is good. That's the right answer. Rock n roll! – Mindexperiment Dec 17 '15 at 18:09

miglio · Answer 2 · 2015-12-17T18:05:50.887

This maybe help you;

$fixedArr = [ 0, 5, 8, 20, 40, 60, 90,135,780 ];
//
$search = 111; // $result = $arr[4] -> 4;
//$search = 110; // $result = $arr[6] -> 6;
//
function leftORright($fixedArr,$search){
    $max = max($fixedArr)+1;
    $near = array(
    'left'=>array('key'=>'none','value'=>'none','bool'=>false),
    'right'=>array('key'=>'none','value'=>$max,'bool'=>false),
    'center'=>array('key'=>'none','value'=>'none','bool'=>false)
    );
    foreach($fixedArr as $k=>$v){
        if($v == $search){
            $near['center']['key'] = $k;
            $near['center']['value'] = $v;
        }
        if($v < $search){
            $near['left']['key'] = $k;
            $near['left']['value'] = $v;
        }
        if($v > $search and $near['right']['value'] > $v){
            $near['right']['key'] = $k;
            $near['right']['value'] = $v;
        }
    }
    //decide near left or right
    $respright = $near['right']['value'] - $search;
    $respleft = $search - $near['left']['value'] ;
    $right_left_equals = false;
    if($near['center']['value'] !== 'none'){
        $near['center']['bool'] = true;
    }else if($respleft < $respright && $near['left']['key']!='none'){
        $near['left']['bool'] = true;
    }else if($respleft > $respright && $near['right']['key']!='none'){
        $near['right']['bool'] = true;
    }else if($near['center']['value'] != 'none'){
        $near['center']['value'] = true;
    }else{
        $right_left_equals = true;
    }
    //var_dump($near);
    //Result is:
    foreach($near as $k=>$v){
        foreach($v as $k2=>$v2){
            if($v2===true){
                var_dump('near is for '.$k);
                return $v;
            }
        }
    }
    //equal for right and left
    if($right_left_equals){
        var_dump('near right left are equals');
        return array($near['right'],$near['left']);
    }
}
$result = leftORright($fixedArr,$search);
var_dump($result);

response:

string 'near is for left' (length=16)

array (size=3)
  'key' => int 6
  'value' => int 90
  'bool' => boolean true

Praveen Kumar Purushothaman · Answer 3 · 2015-12-17T16:49:11.853

0

Use array_search:

array_search — Searches the array for a given value and returns the corresponding key if successful

$search = array_search(42, $fixedArr); // -> 4
$search = array_search(110, $fixedArr); // -> 6

Your question is similar to finding the closest one:

<?php
    $fixedArr = [ 0, 5, 8, 20, 40, 60, 90, 135, 780 ];
    function getClosest($search, $arr) {
        $left = 0;
        foreach ($arr as $val) {
            if ($search > $val)
                $left = $val;
            elseif ($search < $val) {
                $right = $val;
                break;
            }
            else {
                $right = $val;
                break;
            }
        }
        return array($left, $right, array_search($left, $arr), array_search($right, $arr), (($search - $left) > ($right - $search) ? array_search($right, $arr) : array_search($left, $arr)));
    }
    print_r(getClosest(4, $fixedArr));
?>

edited Dec 17 '15 at 16:49

answered Dec 17 '15 at 16:30

Praveen Kumar Purushothaman

164,888
24
203
252

What if `42` is not in array?? – Niranjan N Raju Dec 17 '15 at 16:36
What I don't understand? https://eval.in/487181 – splash58 Dec 17 '15 at 16:36
@NiranjanNRaju Updated. – Praveen Kumar Purushothaman Dec 17 '15 at 16:36
from [here](http://stackoverflow.com/questions/5464919/php-nearest-value-from-an-array)?? – Niranjan N Raju Dec 17 '15 at 16:36
@NiranjanNRaju Yes, updated that. – Praveen Kumar Purushothaman Dec 17 '15 at 16:37
any difference from my answer?? – Niranjan N Raju Dec 17 '15 at 16:37
@NiranjanNRaju Actually no. So I am voting your answer up. I answered first! `:P` That's the only difference. – Praveen Kumar Purushothaman Dec 17 '15 at 16:37
Hey dude. sorry for negative vote. but your answer is not correct. – Monty Dec 17 '15 at 16:38
@Monty Thanks. Can you please explain how can I make the answer better, will surely edit it. `:)` – Praveen Kumar Purushothaman Dec 17 '15 at 16:39
need the "left-near" key.. – Mindexperiment Dec 17 '15 at 16:40
@Mindexperiment Working on it. `:)` – Praveen Kumar Purushothaman Dec 17 '15 at 16:40
@Mindexperiment Updated correctly. – Praveen Kumar Purushothaman Dec 17 '15 at 16:49
@Mindexperiment This now gives the left, right, and correct one's address too! – Praveen Kumar Purushothaman Dec 17 '15 at 16:55
@Mindexperiment : Yes i have solution. check my answer. – Monty Dec 17 '15 at 17:13

Monty · Answer 4 · 2015-12-17T18:00:13.073

Try this : It will Work in all cases.

$fixedArr = [ 0, 5, 8, 20, 40, 60, 90, 135, 780 ];
$find = 14;
for ($i=0; $i < count($fixedArr); $i++) {
    if($fixedArr[$i] <= $find){
        $large[] = $fixedArr[$i];       
    }else{
        $small[] = $fixedArr[$i];
    }
}
$near1 = max($large);
$near2 = min($small);
echo "Value $find coming in between $near1 and $near2";
echo "<br>";
if($find >= ($near1 + $near2) / 2){
    echo "Closed Value is : $near2";
}else{
    echo "Closed Value is : $near1";
}

Output:

Value 14 coming in between 8 and 20
Closed Value is : 20

Find key of array based on variable value between array values

4 Answers4