操作PHP数组以将小值分组以在饼图中使用

Question

I am looking for ideas on some PHP for the following -

I have an array of numerical values that feed a pie chart (created with High Charts). These values vary in size depending what the chart is showing and the array might be up to 100 values long.

The problem is that if I send these values to the pie and a lot of the values are low, it ends up with the smaller values creating lots of pie 'slices' that are too small to read and so ineffective. What I want to do is group all the values under a threshold % into a group called Other.

From research I can't seem to do this natively in High Charts but I think I should be able to do it with PHP. So the PHP would have to -

1. Take an array (100, 96, 72, 25, 3, 2, 1, 1, 1) etc
2. Work out the total of the values and thus % of each - (33%, 32%, 23%, 8%, 1%, 0.6%, 0.3%, 0.3%, 0.3%) etc
3. Remove any values below a certain % ie 1% so that the array becomes - (100, 96, 72)
4. Add back into the array a value representing the total of those removed (100, 96, 72, 33)
5. The array can now be sent to the pie

Any ideas please?

Answer 1

My solution using array_filter():

$input = array(100, 96, 72, 25, 3, 2, 1, 1, 1);

$thresh = 0.01;          // Threshold; 0.01 == 1%
$extra  = 0;             // The sum of the combined slices ('Other')

// Compute the sum of all values (needed for the percentages)
$sum    = array_sum($input);
$output = array_merge(
    // Process the input list (combine and remove)
    array_filter(
        $input,
        function ($item) use ($sum, $thresh, &$extra) {
            // Compute the percentage and check it against the threshold
            if ($item / $sum < $thresh) {
                // Too small
                $extra += $item;     // Add it to 'Other'
                return FALSE;        // Remove it from the input list
            } else {
                // Above the threshold
                return TRUE;         // Let it go to the final list
            }
        }
    ),
    // Don't forget to add the combined value to the output
    array($extra)
);

And a solution using array_reduce():

$input = array(100, 96, 72, 25, 3, 2, 1, 1, 1);

$thresh = 0.01;          // Threshold; 0.01 == 1%
$extra  = 0;             // The sum of the combined slices ('Other')

// Compute the sum of all values (needed for the percentages)
$sum    = array_sum($input);
$output = array_merge(
    // Process the input list (keep, remove, combine)
    array_reduce(
        $input,
        function (array $carry, $item) use ($sum, $thresh, &$extra) {
            // Compute the percentage and check it against the threshold
            if ($item / $sum < $thresh) {
                // Too small
                $extra += $item;     // Add it to 'Other'
            } else {
                // Above the threshold
                $carry[] = $item;    // Put it into the "reduced" list
            }
            // Always return $carry (the reduced list)
            return $carry;
        },
        // Start with an empty list; here will be added the values above the threshold
        array()
    ),
    // Don't forget to add the combined value to the output
    array($extra)
);