如何使用PHP对范围中的数字进行分组

Question

假设我在数组中有以下数字序列:

$numbers = array(1,3,2,23,24,25,26, 8)

如何在范围内打印它们,例如:

数字是1-3,23-26,8.

Answer 1

这是一个简单的版本,创建groups包含您的范围

<?php
$numbers = array(1,3,2,23,24,25,26,8);
sort($numbers);
$groups = array();

for($i = 0; $i < count($numbers); $i++)
{
    if($i > 0 && ($numbers[$i - 1] == $numbers[$i] - 1))
        array_push($groups[count($groups) - 1], $numbers[$i]);
    else // First value or no match, create a new group
        array_push($groups, array($numbers[$i])); 
}

foreach($groups as $group)
{
    if(count($group) == 1) // Single value
        echo $group[0] . "\n";
    else // Range of values, minimum in [0], maximum in [count($group) - 1]
        echo $group[0] . " - " . $group[count($group) - 1] . "\n";
}

输出是

1 - 3
8
23 - 26

现在,如果范围的顺序很重要,就像您在问题中所描述的那样,您仍然可以对您的组进行排序......从我所看到的,您希望范围首先跟随单个值吗？这可以通过添加来完成

function groupRanges($a, $b)
{
    if(count($a) == 1)
        if(count($b) == 1)
            return 0; // equal
        else
            return 1; // so $b is considered less than

    if(count($b) == 1)
        return -1; // so $a is considered less than

    return 0; // both are ranges, keep them there... could be adjusted to compare the size of each range
}

usort($groups, "groupRanges");

就在之前foreach,输出变为:

1 - 3
23 - 26
8