Javascript从数组中的高点组中挑选出峰值数

Question

很难用标题来描述它，但从这里的描述和代码中应该很清楚。我试图从一组峰值中挑选出数组中的最高数字，然后进入下一组并从下一组高点中获取下一个峰值数。

所以例如在这个数组中：

const arr = [939, 1301, 253, 1380, 1037, 2279, 2462, 2193, 2121, 1424, 506, 2411, 2456, 2295, 915, 1276, 1532, 1359, 985, 2182, 2407, 2103, 2392, 2294, 765, 1195, 1537, 1409, 858, 1971, 2214, 1311, 1326, 1383, 1231, 1141]

我想2462从大约 的第一组峰值中1037, 2279, 2462, 2193挑选出来，然后继续2456从大约 的下一组中挑选出来506, 2411, 2456, 2295, 915。这些组的位置未知，只需找到它们并从每个组中选择一个最高的数字即可。

这是我目前拥有的功能，但它不能 100% 工作并且不适用于某些数组。

let currHigh = 0, store = [], limit = 2100;

for (let s = 0; s < arr.length; s++) {

    if (arr[s] > limit && currHigh === 0) {

        currHigh = arr[s]

    } else if (arr[s] > limit && arr[s] > currHigh) {

        currHigh = arr[s];

    } else if (arr[s] < currHigh) {

        if (arr[s] < limit) {

            store.push(currHigh); currHigh = 0;

        }

    }

}

console.log(store)

高点总是非常相似（2000+），数字组的位置相似但不一样，所以我不能真正依赖它。

所以第一个数组和预期/期望的输出是：

const arr = [939, 1301, 253, 1380, 1037, 2279, 2462, 2193, 2121, 1424, 506, 2411, 2456, 2295, 915, 1276, 1532, 1359, 985, 2182, 2407, 2103, 2392, 2294, 765, 1195, 1537, 1409, 858, 1971, 2214, 1311, 1326, 1383, 1231, 1141]

Outputted Peaks: [2462, 2456, 2407, 2294, 2214]

另一个具有预期/所需输出的示例数组：

const arr =  [1365, 1324, 1013, 1220, 1259, 2204, 2212, 1938, 1882, 1545, 1236, 2090, 2614, 1949, 1307, 1628, 1780, 1263, 1184, 2184, 1411, 1306, 2010, 2057, 1339, 1624, 2480, 2575, 2425, 2617, 2479, 1929, 1805, 1869, 1341, 1104, 2195, 1661, 1174, 1447, 1761, 1362, 1430]

Outputted Peaks: [2212, 2614, 2184, 2480, 2617, 2195]

编辑：为了避免混淆，想象一下，如果您要获取给定数组中的值并将它们绘制在图形上，图形中会有几个相互隔开的峰值。我需要一个函数来获得这些峰值。查找组只是查找峰值的一种方法。它们就像迷你山。因此，例如，您不会希望获得位于“山的一侧”的高数字。

编辑：附加图像来解释峰值。紧挨着另一个高数的高数不是峰，只有一小组相邻数中的最高数才是峰。 

最终编辑：此图最好地说明了它，因为很难想象仅查看数组的图：

https://jsbin.com/nicuciquru/1/edit?js,output

所以我在这里需要的是[1301, 1380, 2462, 2456, 1532, 2407, 2492, 1537, 2214, 1383]你可以在图表上看到的峰值。然后从那里可以使用阈值轻松过滤这些峰值，例如消除低于 2000 的任何峰值。

Answer 1

这是一个查找样本数组中所有峰值的函数：&nbsp; &nbsp; const chart = [939, 1301, 253, 1380, 1037, 2279, 2462, 2193, 2121, 1424, 506, 2411, 2456, 2295, 915, 1276, 1532, 1359, 985, 2182, 2407, 2103, 2392, 2294, 765, 1195, 1537, 1409, 858, 1971, 2214, 1311, 1326, 1383, 1231, 1141]&nbsp; &nbsp; const findPeaks = chart => chart.reduce((agg, current, i) => {&nbsp; &nbsp; &nbsp; &nbsp; const prev = chart[i - 1];&nbsp; &nbsp; &nbsp; &nbsp; const next = chart[i + 1];&nbsp; &nbsp; &nbsp; &nbsp; return current > prev && current > next ? [...agg, current] : agg;&nbsp; &nbsp; }, []);&nbsp; &nbsp; const peaks = findPeaks(chart);&nbsp; &nbsp; console.log('peaks', peaks);这记录： [1301, 1380, 2462, 2456, 1532, 2407, 2392, 1537, 2214, 1383]这与您的问题的预期输出不匹配，但它确实对“峰值是什么”给出了准确的答案。在这种情况下，“峰值”被定义为任何前任和后继都低于自身的数字。即 [1, 100, 1] 给出 100。 [1, 2, 3, 100, 3, 2, 100, 1] 给出 [100, 100]更新根据您的反馈，这里有一个函数，它需要一个峰的每边距离为 2 。结果仍然与您的问题不同，但这符合新表达的标准：const findPeaks = chart => chart.reduce((agg, current, i) => {&nbsp; &nbsp; &nbsp; &nbsp; const twoBack = chart[i - 2];&nbsp; &nbsp; &nbsp; &nbsp; const prev = chart[i - 1];&nbsp; &nbsp; &nbsp; &nbsp; const next = chart[i + 1];&nbsp; &nbsp; &nbsp; &nbsp; const twoForward = chart[i + 2];&nbsp; &nbsp; &nbsp; &nbsp; return (twoBack < prev && prev < current) && (current > next&nbsp; && next > twoForward )&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; ? [...agg, current]&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; : agg;&nbsp; &nbsp; }, []);对于上述输入，这会产生：[2462, 2456, 1532, 1537, 1383]更新 2这是找到所有峰值、计算出中值并返回大于中值的所有峰值的代码版本。这是与您在问题中要求的最接近的结果：const findPeaks = chart => {&nbsp; &nbsp; const peaks = chart.reduce((agg, current, i) => {&nbsp; &nbsp; const twoBack = chart[i - 2];&nbsp; &nbsp; const prev = chart[i - 1];&nbsp; &nbsp; const next = chart[i + 1];&nbsp; &nbsp; const twoForward = chart[i + 2];&nbsp; &nbsp; return (prev < current) && (current > next)&nbsp;&nbsp; &nbsp; ? [...agg, current]&nbsp;&nbsp; &nbsp; : agg;&nbsp; &nbsp; }, []);&nbsp; &nbsp; const mean = peaks.reduce((a, b) => a + b) / peaks.length;&nbsp; &nbsp; return peaks.filter(peak => peak > mean);}这个的输出是：[2462, 2456, 2407, 2392, 2214]

Answer 2

没有更精确地定义所需的输出（例如，什么被认为是一个组？），这是一个简单的算法：1) 将数组拆分为“低”和“高”序列。例如[1, 10000, 100, 101, 20000, 20050, 30, 10, 2]=> [1], [10000], [100, 101], [20000, 20050], [30, 10, 2]。2) 返回每个高序列的最大值。let peaks = arr => {&nbsp; &nbsp; let isHigh = a => a >= 2000;&nbsp; &nbsp; let isLow = a => !isHigh(a);&nbsp; &nbsp; let groups = [];&nbsp; &nbsp; while (arr.length && arr.some(isHigh)) {&nbsp; &nbsp; &nbsp; &nbsp; arr.splice(0, arr.findIndex(isHigh));&nbsp; &nbsp; &nbsp; &nbsp; groups.push(arr.splice(0, arr.findIndex(isLow)));&nbsp; &nbsp; }&nbsp; &nbsp; return groups.map(group => Math.max(...group));};const arr = [939, 1301, 253, 1380, 1037, 2279, 2462, 2193, 2121, 1424, 506, 2411, 2456, 2295, 915, 1276, 1532, 1359, 985, 2182, 2407, 2103, 2392, 2294, 765, 1195, 1537, 1409, 858, 1971, 2214, 1311, 1326, 1383, 1231, 1141];console.log(peaks(arr));const arr2 = [1365, 1324, 1013, 1220, 1259, 2204, 2212, 1938, 1882, 1545, 1236, 2090, 2614, 1949, 1307, 1628, 1780, 1263, 1184, 2184, 1411, 1306, 2010, 2057, 1339, 1624, 2480, 2575, 2425, 2617, 2479, 1929, 1805, 1869, 1341, 1104, 2195, 1661, 1174, 1447, 1761, 1362, 1430];console.log(peaks(arr2));

Answer 3

为什么不保持简单？var arr = [1,6,4,3,9,11];var peaks = arr.sort((a, b) => a - b).reverse();输出为：[11, 9, 6, 4, 3, 1]然后：var top5 = peaks.slice(0,5);结果是：[11, 9, 6, 4, 3]或者你的数学的整个代码：const peaks1 = [939, 1301, 253, 1380, 1037, 2279, 2462, 2193, 2121, 1424, 506, 2411, 2456, 2295, 915, 1276, 1532, 1359, 985, 2182, 2407, 2103, 2392, 2294, 765, 1195, 1537, 1409, 858, 1971, 2214, 1311, 1326, 1383, 1231, 1141];const peaks2 =&nbsp; [1365, 1324, 1013, 1220, 1259, 2204, 2212, 1938, 1882, 1545, 1236, 2090, 2614, 1949, 1307, 1628, 1780, 1263, 1184, 2184, 1411, 1306, 2010, 2057, 1339, 1624, 2480, 2575, 2425, 2617, 2479, 1929, 1805, 1869, 1341, 1104, 2195, 1661, 1174, 1447, 1761, 1362, 1430];const peaks = [peaks1, peaks2];function getPeaks(arr){&nbsp; &nbsp; let peaks = [];&nbsp; &nbsp; for(let i=0;i<arr.length;i++){&nbsp; &nbsp; &nbsp; &nbsp; let currPeak = arr[i].sort((a, b) => a - b).reverse().slice(0,1)[0];&nbsp; &nbsp; &nbsp; &nbsp; peaks.push(currPeak);&nbsp; &nbsp; }&nbsp; &nbsp; return peaks.sort((a, b) => a - b).reverse();}let result = getPeaks(peaks);结果应该是：[2617, 2462]