计算范围之间的值

Question

我有两个数组，一个是值，另一个是范围：

$ranges = array(10,15,30);

$values = array(1,4,12,15,27,32);

我想计算每个范围之间的值的数量，例如：

$output = array(

    "<10" => 2, // number of values < 10

    "10-15" => 1, // number of values >= 10 && < 15

    "15-30" => 2, // number of values >= 15 && < 30

    ">=30" => 1, // number of values > 30

);

显然，ranges并且values是动态的，不能硬编码if-conditions。

到目前为止我所做的工作：

$output = array();

foreach ( $values as $val ) {

    foreach ( $ranges as $k => $range ) {

        if ( $k == 0 ) { // first range

            $max = $range;

            $label = '<' . $max;

            if ( $val < $max ) {

                $output[$label] += 1;

            }

        } else if ( $k == count($ranges) - 1 ) { // last range

            $min = $ranges[$k-1];

            $max = $range;

            $label = $min . '-' . $max;

            if ( $val >= $min && $val < $max ) {

                $output[$label] += 1;

            }

            $min = $range;

            $label = '>=' . $min;

            if ( $val >= $min ) {

                $output[$label] += 1;

            }

        } else {

            $min = $ranges[$k-1];

            $max = $range;

            $label = $min . '-' . $max;

            if ( $val >= $min && $val < $max ) {

                $output[$label] += 1;

            }

        }

    }

}

print_r($output);

这似乎很昂贵，我真的不确定。有没有更简单的方法来实现我正在寻找的东西？

Answer 1

您可以通过在 $ranges 数组的开头和结尾添加限制值来简化逻辑，然后只需成对处理整个数组。<?php$ranges = [10,15,30];$values = [1,4,12,15,27,32];\array_push($ranges, null); // append null to array\array_unshift($ranges, null); // prepend null to array$output = [];$count = \count($ranges);for ($i = 0; $i < $count - 1; $i++) {&nbsp; &nbsp; $output[] = ['start' => $ranges[$i], 'end' => $ranges[$i+1], 'count' => 0];}foreach ($values as $value) {&nbsp; &nbsp; foreach ($output as $key => $range) {&nbsp; &nbsp; &nbsp; &nbsp; if (&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;($range['start'] === null || $range['start'] <= $value) &&&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;($range['end'] === null || $range['end'] > $value)&nbsp; &nbsp; &nbsp; &nbsp; ) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $output[$key]['count']++;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}var_dump($output);

Answer 2

$ranges首先使用数组中的键（使用）创建一个归零数组array_fill_keys()，再加上一个用于“超过”最后一个条目的值。循环遍历每个值并根据范围检查它，如果找到它，它只会将相应的计数加 1 并停止查找。如果在完成循环后，该值大于最后一个范围，则将 1 添加到“over”条目。$ranges = array(10,15,30);$values = array(1,4,12,15,27,32);$rangeCount = array_fill_keys($ranges, 0);$rangeCount[ "over" ] = 0;foreach ( $values as $value )&nbsp; &nbsp;{&nbsp; &nbsp; foreach ( $ranges as $range )&nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; if ( $value < $range )&nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $rangeCount [ $range ]++;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; if ( $value >= $range )&nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; $rangeCount[ "over" ]++;&nbsp; &nbsp; }}print_r($rangeCount);这使...Array(&nbsp; &nbsp; [10] => 2&nbsp; &nbsp; [15] => 1&nbsp; &nbsp; [30] => 2&nbsp; &nbsp; [over] => 1)只是为了添加一个只做一个循环的优化版本。但假设这些值是按升序排列的。每次它通过“当前”范围时，它都会移动到下一个输出计数器，最后一部分甚至不会循环超过最大值，它会从总计数中减去当前计数并中断...$currentRange = 0;$numberValues = count($values);$numberRanges = count($ranges);$rangeCount = array_fill(0, $numberRanges, 0);$rangeCount[ "over" ] = 0;foreach ( $values as $count => $value )&nbsp; &nbsp;{&nbsp; &nbsp; if ( $value >= $ranges[$currentRange] )&nbsp; &nbsp;{&nbsp; &nbsp; &nbsp; &nbsp; $currentRange++;&nbsp; &nbsp; &nbsp; &nbsp; if ( $currentRange >= $numberRanges )&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $rangeCount[ "over" ] = $numberValues - $count;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; $rangeCount[$currentRange]++;}print_r($rangeCount);

Answer 3

以下解决方案首先按升序/非降序对范围进行排序。然后，我们创建一个range_map它是所有可能范围的集合$ranges。然后，我们遍历所有值$values并进行二进制搜索以$ranges获得特定值所属的确切范围索引。在下面的代码中，精确索引存储在$low.然后，我们只需通过取范围键$range_map并将其计数器加 1 来收集计数。这比嵌套循环更快，因为嵌套循环的时间复杂度O(m*n)是m大小$ranges和n大小$values，而当前解决方案的时间复杂度O(m logm) + O(n logm)是m大小$ranges和n大小$values。片段：<?php$ranges = array(10,15,30);$values = array(1,4,12,15,27,32);sort($ranges);$range_map = [];$ptr = 0;foreach($ranges as $index => $value){&nbsp; &nbsp; if($index === 0) $range_map[$ptr++] =&nbsp; "<" . $value;&nbsp; &nbsp; if($index > 0) $range_map[$ptr++] = $ranges[$index - 1] . "-" . $value;&nbsp; &nbsp; if($index === count($ranges) - 1) $range_map[$ptr++] = ">=" . $value;}$result = [];foreach($values as $value){&nbsp; &nbsp; $low = 0; $high = count($ranges) - 1;&nbsp; &nbsp; while($low <= $high){&nbsp; &nbsp; &nbsp; &nbsp; $mid = $low + intval(($high - $low) / 2);&nbsp; &nbsp; &nbsp; &nbsp; if($value === $ranges[ $mid ]){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $low = $mid + 1;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; break;&nbsp; &nbsp; &nbsp; &nbsp; }else if($value < $ranges[ $mid ]){&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $high = $mid - 1;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; }else{&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $low = $mid + 1;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; if(!isset($result[$range_map[$low]])) $result[$range_map[$low]] = 0; // get the range key from range_map&nbsp; &nbsp; $result[$range_map[$low]]++; // increment the value for that range}print_r($result);演示： https ://3v4l.org/JcYBv

Answer 4

假设您有预先排序的范围和值。<?php$ranges = array(10,15,30);$values = array(1,4,12,15,27,32);$lower = null;$i = 0;$upper = $ranges[$i];foreach($values as $item) {&nbsp; &nbsp; if(!is_null($upper) && $item >= $upper) {&nbsp; &nbsp; &nbsp; &nbsp; $lower = $upper;&nbsp; &nbsp; &nbsp; &nbsp; $upper = $ranges[++$i] ?? null;&nbsp; &nbsp; }&nbsp; &nbsp; $result["$lower<$upper"][] = $item;}var_export(array_map('count', $result));输出：array (&nbsp; &nbsp; '<10' => 2,&nbsp; &nbsp; '10<15' => 1,&nbsp; &nbsp; '15<30' => 2,&nbsp; &nbsp; '30<' => 1,&nbsp; )