如何通过多个键，字符串和整数的值对多维数组进行排序

Question

I have an array of people (lawmakers) listing their level, state, chamber and district. What I'd like is to sort the array based on the values of these 4 keys, but with a custom order since some of these values are strings. For example, I'd want to first sort by "level" with the order of ("federal","state", then anything else), then state in alphabetical order ascending, then chamber by ("governor","upper","lower", then anything else), then district in number order ascending. Here's a shortened example of the array I'm using.

Array
(
[0] => stdClass Object
    (
        [district] => 15
        [state] => fl
        [level] => state
        [chamber] => upper

    )

[1] => stdClass Object
    (
        [district] => 50
        [state] => fl
        [level] => state
        [chamber] => lower
    )
[2] => stdClass Object
    (
        [district] => 0
        [state] => fl
        [level] => state
        [chamber] => governor

    )
)

Answer 1

@BusyBeaver's solution cmp() / compare() function is quite complex and difficult to update if you want to change order or, God forbid, add another field!

this was what I came up with:

<?php
function sortValue($key, $value)
{
    static $arrValueOrder = [
        'level' => ['federal', 'state'],
        'chamber' => ['governor', 'upper', 'lower']
    ];

    if (array_key_exists($key, $arrValueOrder)) {
        if (($result = array_search($value, $arrValueOrder[$key])) === false) {
            $result = count($arrValueOrder[$key]);
        }
    } else {
        $result = $value;
    }
    return $result;
}

function cmp($a, $b)
{
    static $arrFieldOrder = ['level', 'state', 'chamber', 'district'];

    $result = 0;
    reset($arrFieldOrder);
    while ($result === 0 && list($key, $value) = each($arrFieldOrder)) {
        $aSortValue = sortValue($value, $a->$value);
        $bSortValue = sortValue($value, $b->$value);
        if ($aSortValue > $bSortValue) {
            $result = 1;
        } elseif ($aSortValue < $bSortValue) {
            $result = -1;
        }
    }
    return $result;
}

// setup some test data
$arrData = [
    (object)['district' => 15, 'state' => 'fl', 'level' => 'state', 'chamber' => 'upper'],
    (object)['district' => 15, 'state' => 'tx', 'level' => 'federal', 'chamber' => 'lower'],
    (object)['district' => 50, 'state' => 'fl', 'level' => 'state', 'chamber' => 'lower'],
    (object)['district' => 15, 'state' => 'tx', 'level' => 'federal', 'chamber' => 'upper'],
    (object)['district' => 0, 'state' => 'fl', 'level' => 'state', 'chamber' => 'governor'],
    (object)['district' => 15, 'state' => 'tx', 'level' => 'federal', 'chamber' => 'governor'],
    (object)['district' => 15, 'state' => 'tx', 'level' => 'federal', 'chamber' => 'foo'],
    (object)['district' => 15, 'state' => 'fl', 'level' => 'federal', 'chamber' => 'upper']
];

// sort it
usort($arrData, 'cmp');

// dump the result
var_dump($arrData);

Answer 2

usort() can solve your problem, you only have to write a good compare function that works as desired.

<?php

$lawmakers = ... // Your lawmakers array.
usort($lawmakers, "cmp");

// returns 0 if equal; -1 if $a < $b; 1 otherwise
function cmp($a, $b) {
    // 1. Compare level: "federal" < "state" < anything else
    if ($a["level"] === "federal" && $b["level"] !== "federal") return -1;
    else if ($a["level"] !== "federal" && $b["level"] === "federal") return 1;
    else if ($a["level"] === "state" && $b["level"] !== "state") return -1;
    else if ($a["level"] !== "state" && $b["level"] === "state") return 1;
    // 2. Compare state: alphabetical order
    if (strcmp($a["state"], $b["state"]) > 0) return 1;
    else if (strcmp($a["state"], $b["state"]) < 0) return -1;
    // 3. Compare chamber: "governor" < "upper" < "lower" < anything else
    if ($a["chamber"] === "governor" && $b["chamber"] !== "governor") return -1;
    else if ($a["chamber"] !== "governor" && $b["chamber"] === "governor") return 1;
    else if ($a["chamber"] === "upper" && $b["chamber"] !== "upper") return -1;
    else if ($a["chamber"] !== "upper" && $b["chamber"] === "upper") return 1;
    else if ($a["chamber"] === "lower" && $b["chamber"] !== "lower") return -1;
    else if ($a["chamber"] !== "lower" && $b["chamber"] === "lower") return 1;
    // 4. Compare district: ascending
    if ($a["district"] < $b["district"]) return -1;
    else if ($a["district"] > $b["district"]) return 1;
    // 5. If we came so far... $a and $b are equals
    return 0;
}
?>

You could also think about an Object-oriented solution (which still needs a compare function...)

<?php

// Testing
$a = new Lawmaker("federal", "fl", "upper", 15);
$b = new Lawmaker("state", "fl", "lower", 7);
$c = new Lawmaker("federal", "fl", "upper", 8);
$d = new Lawmaker("other", "wy", "governor", 1);
$lawmakers = Array($a, $b, $c, $d);
mysort($lawmakers);
print_r($lawmakers);



// Class Lawmaker to define Lawmaker object
class Lawmaker
{
    // Properties declaration
    public $level;
    public $state;
    public $chamber;
    public $district;

    // Lawmaker constructor
    function __construct($level, $state, $chamber, $district) {
        $this->level = $level;
        $this->state = $state;
        $this->chamber = $chamber;
        $this->district = $district;
    }

    // Compare $this Lawmaker with $other Lawmaker
    // returns 0 if equal; -1 if $this < $other; 1 otherwise
    public function compare($other) {
        // 1. Compare level: "federal" < "state" < anything else
        if ($this->level === "federal" && $other->level !== "federal") return -1;
        else if ($this->level !== "federal" && $other->level === "federal") return 1;
        else if ($this->level === "state" && $other->level !== "state") return -1;
        else if ($this->level !== "state" && $other->level === "state") return 1;
        // 2. Compare state: alphabetical order
        if (strcmp($this->state, $other->state) > 0) return 1;
        else if (strcmp($this->state, $other->state) < 0) return -1;
        // 3. Compare chamber: "governor" < "upper" < "lower" < anything else
        if ($this->chamber === "governor" && $other->chamber !== "governor") return -1;
        else if ($this->chamber !== "governor" && $other->chamber === "governor") return 1;
        else if ($this->chamber === "upper" && $other->chamber !== "upper") return -1;
        else if ($this->chamber !== "upper" && $other->chamber === "upper") return 1;
        else if ($this->chamber === "lower" && $other->chamber !== "lower") return -1;
        else if ($this->chamber !== "lower" && $other->chamber === "lower") return 1;
        // 4. Compare district: ascending
        if ($this->district < $other->district) return -1;
        else if ($this->district > $other->district) return 1;
        // 5. If we came so far... $this and $other are equals
        return 0;
    }
}

function mysort(&$array) {
  // Simple selection sort. You can implement any sorting algorithm.
  for ($i = 0; $i < count($array); $i++) {
    $pos = $i;
    // Search for minimum
    for ($j = $i+1; $j < count($array); $j++) {
      if ($array[$j]->compare($array[$pos]) < 0) {
        $pos = $j;
      }
    }
    // Swap
    $temp = $array[$i];
    $array[$i] = $array[$pos];
    $array[$pos] = $temp;
  }
  // Done.
}