我一直在绞尽脑汁试图解决这个挑战。
PHP 默认的
sort
函数没有提供解决方案,但是使用 usort
也不容易。
这就是我要解决的问题。我按以下顺序创建了一个数组:
$data = array( '_', '@', ...range(-10, 10), ...range('A', 'Z'), ...range('a', 'z') )
现在我想使用
usort
对这个数组进行排序,以便:
negative
数字在前,uppercase
接下来是字母_
& @
字符如下lowercase
字母如下positive
数字结束订单有点像:
/*
array(
"-10",
"-9",...
"A",
"B",...
"_",
"@", // @ may come first
"a",
"b",...
"1",
"2"...
) */
有什么方法可以解决这个问题吗?
usort($data, function($a,$b) {
if( is_numeric($a) && (int)$a < 0 ) return -1; // take negative number to start
else {
if( !is_numeric($a) ) {
if( is_numeric($b) && (int)$b > 0 ) return -1;
else return $b < $a ? 1 : 0;
} else return 1; // take positive number to end
}
});
将其视为一个层次结构。您有 5 个不重叠的“类”要排序:负数、大写、符号、小写、正数。所以首先确定类别排序,如果两个项目的类别相同,则比较它们的值。
class MySorter {
const CLASS_NUM_NEG = 0;
const CLASS_STR_UC = 1;
const CLASS_STR_OT = 2;
const CLASS_STR_LC = 3;
const CLASS_NUM_POS = 4;
static function get_class($item) {
switch(gettype($item)) {
case 'integer':
case 'float':
return ($item < 0) ? self::CLASS_NUM_NEG : self::CLASS_NUM_POS;
case 'string':
$ord = ord($item[0]);
// note: below ord() calls are illustrative, and
// should be replaced with non-computed values to
// avoid repetitive work.
if( $ord >= ord('A') && $ord <= ord('Z')) {
return self::CLASS_STR_UC;
} else if( $ord >= ord('a') && $ord <= ord('z')) {
return self::CLASS_STR_LC;
} else {
return self::CLASS_STR_OT;
}
default:
throw new \Exception("Unhandled type: " . gettype($item));
}
}
static function compare($a, $b) {
$res = self::get_class($a) <=> self::get_class($b);
if( $res !== 0 ) { return $res; }
return $a <=> $b;
}
}
$data = [ '_', '@', ...range(-10, 10), ...range('A', 'Z'), ...range('a', 'z') ];
usort($data, ['MySorter', 'compare']);
echo json_encode($data);
旁白:类可以用作 ersatz 命名空间以包含相关的函数和变量,这样您就可以比完全内联的东西或将东西转储到本地/全局命名空间中更好地封装逻辑。
输出:
[-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","@","_","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z",0,1,2,3,4,5,6,7,8,9,10]
这感觉非常干净,易于阅读,并且易于扩展/维护。 使用速记三元组和宇宙飞船运算符比较的后备比较。
代码:(演示)
usort($data, fn($a, $b) =>
[is_int($b) && $b < 0] <=> [is_int($a) && $a < 0] // prioritize negatives
?: (ctype_upper((string) $b) <=> ctype_upper((string) $a)) // prioritize uppercase letters
?: (in_array($b, ['_', '@']) <=> in_array($a, ['_', '@'])) // prioritize symbols
?: ($a <=> $b) // sort normally
);
var_export($data);
或者,如果性能是一个问题,通过准备评估数组来减少所需函数调用的总数,然后调用
array_multisort()
。 (演示)
$negatives = [];
$uppers = [];
$symbols = [];
foreach ($data as $v) {
$negatives[] = is_int($v) && $v < 0;
$uppers[] = ctype_upper((string) $v);
$symbols[] = in_array($v, ['_', '@']);
}
array_multisort(
$negatives,
SORT_DESC,
$uppers,
SORT_DESC,
$symbols,
SORT_DESC,
$data
);
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