Creating an array for histogram

frequency_distribution_table.php

<?php

$data = array(
    164, 150, 132, 144, 125, 149, 145, 146,
    158, 140, 147, 136, 148, 152, 144, 168,
    126, 138, 176, 163, 119, 154, 165, 146,
    173, 142, 147, 135, 153, 140, 135, 161,
    145, 135, 142, 150, 156, 145, 128, 157
);

$maxBins = 0;  // if no maximum bins needed set to 0.
$maxRangePerBin = 10; // if no range per bin needed, set to 0.

$min = min($data);
$max = max($data);

$labels = [];
$res = [];

if ($maxRangePerBin > 0) {
    $expectedBins = ceil(($max - $min) / $maxRangePerBin);
    $valuePerBin = $maxRangePerBin;
} else {
    $maxBins = $maxBins > 0 ? $maxBins : 10;  // if no maximum number of bins set, set maxBins to 10.
    $valuePerBin = ceil(($max - $min) / $maxBins);
    $expectedBins = $maxBins;
}

if ($maxBins > 0) {
    $totalBins = $maxBins;
} else {
    $totalBins = $expectedBins;
}

sort($data);

for ($i = 0; $i < $totalBins; $i++) {
    $count = 0;
    if ($maxBins > 0 && $i == $totalBins - 1) {
        foreach ($data as $key => $number) {
            $count++;
            unset($data[$key]);
        }
    } else {
        foreach ($data as $key => $number) {
            if ($number <= (($min + ($valuePerBin - 1)) + ($i * $valuePerBin))) {
                $count++;
                unset($data[$key]);
            }
        }
    }
    if ($maxBins > 0 && $i == $totalBins - 1 && $maxRangePerBin != 0) {
        if ($count > 0) {
            $labels[$i] = ">= " . ($min + ($i * $valuePerBin));
            $res[$i] = $count;
        }
    } else if (count($data) > 0 || $count > 0) {
        $res[$i] = $count;
        $labels[$i] = ($min + ($i * $valuePerBin)) . '-' . (($min + ($valuePerBin - 1)) + ($i * $valuePerBin));
    }


}

var_dump(array("labels" => $labels, "values" => $res));

// Output when maxBins = 0 and maxRangePerBin = 10:
// 119-128 => 4
// 129-138 => 6
// 139-148 => 14
// 149-158 => 9
// 159-168 => 5
// 169-178 => 2