我正在用Javascript构建一个四分位数排序器。 Codepen在下面。将表中的标题拖到表上方的灰色区域以查看表的排序。 https://codepen.io/carbondesign/pen/MPPRPW?editors=0010
此代码有效，但有两个问题： 我写了很长的篇幅，以便自己解决问题。 2.按第三列排序不起作用。
要查看＃2，请将“区域”拖动到排序器框中（表格上方的灰色区域），表格将按预期进行排序（俄罗斯是最大的国家）。将“人口”拖到分类器区域，表格将按预期进行排序（中国是最大，人口最多的国家）。将“人口增长率”拖到分拣机区域中，这几乎可行，但效果不佳。我得到双重值，排序顺序应如下，伊拉克是最大，人口最多的国家，增长率最高。
有问题的代码从154行开始（再次，我是故意写出来的）：
let thirdBuckets = [[],[],[],[]]
secondBuckets.forEach( (secondbucket) => {
secondbucket.forEach((currentVal) => {
if(currentVal[sorters[i]] !== null){
if(currentVal[sorters[i]] > columnSummary[sorters[i]].min && currentVal[sorters[i]] <= columnSummary[sorters[i]].first){
thirdBuckets[0].push(currentVal);
}
if(currentVal[sorters[i]] > columnSummary[sorters[i]].first && currentVal[sorters[i]] <= columnSummary[sorters[i]].mean){
thirdBuckets[1].push(currentVal);
}
if(currentVal[sorters[i]] > columnSummary[sorters[i]].mean && currentVal[sorters[i]] <= columnSummary[sorters[i]].third){
thirdBuckets[2].push(currentVal);
}
if(currentVal[sorters[i]] > columnSummary[sorters[i]].third && currentVal[sorters[i]] <= columnSummary[sorters[i]].max){
thirdBuckets[3].push(currentVal);
}
}else{
nullBucket.push(currentVal);
}
});
secondbucket.length = 0;
thirdBuckets.forEach((thirdbucket) => {
thirdbucket.forEach((currentVal) => {
secondbucket.push(currentVal)
})
});
})
console.log(thirdBuckets);
results.length = 0;
secondBuckets.forEach((secondbucket) => {
// regularSort(secondbucket, sorters[i])
secondbucket.forEach((currentVal) => {
results.push(currentVal)
})
})
}
感谢所有建议。
答案 0 :(得分：1)
给出一系列排序方法：
[ (a, b) -> n ]
您可以通过迭代方法并应用它们直到第一个返回-1或1来创建组合排序方法。您可以使用递归来做到这一点，但是在一个简单的循环中会更容易：
// Using recursion
const chainSortRec = ([s = Done, ...sorters]) =>
(a, b) => s === Done
? 0
: s(a, b) || chainSortRec(sorters)(a, b);
// Using a regular loop
const chainSort = (sorters) => (a, b) => {
for (let i = 0; i < sorters.length; i += 1) {
const res = sorters[i](a, b);
if (res) return res;
}
return 0;
};
一个基于多个排序器对一组数组进行排序的示例：
const numSort = (a, b) => a > b ? -1 : a < b ? 1 : 0;
const sortBy0 = ([a ], [b ]) => numSort(a, b);
const sortBy1 = ([,a ], [,b ]) => numSort(a, b);
const sortBy2 = ([,,a], [,,b]) => numSort(a, b);
const Done = Symbol();
// Applies the first sort method, if any.
// If it returns 0, it recurses to the next.
// When out of sort methods, it returns 0.
const chainSortRec = ([s = Done, ...sorters]) =>
(a, b) => s === Done
? 0
: s(a, b) || chainSortRec(sorters)(a, b);
const data = [
[2, 0, 0],
[1, 0, 0],
[1, 1, 1],
[1, 1, 0],
[3, 0, 0],
];
console.log(
data
.sort(chainSortRec([sortBy0, sortBy1, sortBy2]))
.map(xs => `[ ${xs} ]`)
.join("\n")
);
这可能只能部分回答您的问题，但是我很难遍历所有代码行以及与UI代码的混合使用...
无论如何，这是一个完整的正在运行的控制台示例，其中包含大量注释，可以提供您所需的结果：
const data = [{"name":"Afghanistan","area":652230,"population":32564342,"populationGrowthRate":2.32},{"name":"Akrotiri","area":123,"population":null,"populationGrowthRate":null},{"name":"Albania","area":28748,"population":3029278,"populationGrowthRate":0.3},{"name":"Algeria","area":2381741,"population":39542166,"populationGrowthRate":1.84},{"name":"American Samoa","area":199,"population":54343,"populationGrowthRate":-0.3},{"name":"Andorra","area":468,"population":85580,"populationGrowthRate":0.12},{"name":"Angola","area":1246700,"population":19625353,"populationGrowthRate":2.77},{"name":"Anguilla","area":91,"population":16418,"populationGrowthRate":2.03},{"name":"Antarctica","area":null,"population":null,"populationGrowthRate":null},{"name":"Antigua and Barbuda","area":443,"population":92436,"populationGrowthRate":1.24},{"name":"Argentina","area":2780400,"population":43431886,"populationGrowthRate":0.93},{"name":"Armenia","area":29743,"population":3056382,"populationGrowthRate":-0.15},{"name":"Aruba","area":180,"population":112162,"populationGrowthRate":1.33},{"name":"Ashmore and Cartier Islands","area":5,"population":null,"populationGrowthRate":null},{"name":"Australia","area":7741220,"population":22751014,"populationGrowthRate":1.07},{"name":"Austria","area":83871,"population":8665550,"populationGrowthRate":0.55},{"name":"Azerbaijan","area":86600,"population":9780780,"populationGrowthRate":0.96},{"name":"Bahamas The","area":13880,"population":324597,"populationGrowthRate":0.84},{"name":"Bahrain","area":760,"population":1346613,"populationGrowthRate":2.41},{"name":"Bangladesh","area":143998,"population":168957745,"populationGrowthRate":1.6},{"name":"Barbados","area":430,"population":290604,"populationGrowthRate":0.31},{"name":"Belarus","area":207600,"population":9589689,"populationGrowthRate":-0.2},{"name":"Belgium","area":30528,"population":11323973,"populationGrowthRate":0.76},{"name":"Belize","area":22966,"population":347369,"populationGrowthRate":1.87},{"name":"Benin","area":112622,"population":10448647,"populationGrowthRate":2.78},{"name":"Bermuda","area":54,"population":70196,"populationGrowthRate":0.5},{"name":"Bhutan","area":38394,"population":741919,"populationGrowthRate":1.11},{"name":"Bolivia","area":1098581,"population":10800882,"populationGrowthRate":1.56},{"name":"Bosnia and 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Lanka","area":65610,"population":22053488,"populationGrowthRate":0.84},{"name":"Sudan","area":1861484,"population":36108853,"populationGrowthRate":1.72},{"name":"Suriname","area":163820,"population":579633,"populationGrowthRate":1.08},{"name":"Svalbard","area":62045,"population":1872,"populationGrowthRate":-0.03},{"name":"Swaziland","area":17364,"population":1435613,"populationGrowthRate":1.11},{"name":"Sweden","area":450295,"population":9801616,"populationGrowthRate":0.8},{"name":"Switzerland","area":41277,"population":8121830,"populationGrowthRate":0.71},{"name":"Syria","area":185180,"population":17064854,"populationGrowthRate":-0.16},{"name":"Taiwan","area":35980,"population":23415126,"populationGrowthRate":0.23},{"name":"Tajikistan","area":143100,"population":8191958,"populationGrowthRate":1.71},{"name":"Tanzania","area":947300,"population":51045882,"populationGrowthRate":2.79},{"name":"Thailand","area":513120,"population":67976405,"populationGrowthRate":0.34},{"name":"Timor-Leste","area":14874,"population":1231116,"populationGrowthRate":2.42},{"name":"Togo","area":56785,"population":7552318,"populationGrowthRate":2.69},{"name":"Trinidad and Tobago","area":5128,"population":1222363,"populationGrowthRate":-0.13},{"name":"Tunisia","area":163610,"population":11037225,"populationGrowthRate":0.89},{"name":"Turkey","area":783562,"population":79414269,"populationGrowthRate":1.26},{"name":"Turkmenistan","area":488100,"population":5231422,"populationGrowthRate":1.14},{"name":"Turks and Caicos Islands","area":948,"population":50280,"populationGrowthRate":2.3},{"name":"Tuvalu","area":26,"population":10869,"populationGrowthRate":0.82},{"name":"Uganda","area":241038,"population":37101745,"populationGrowthRate":3.24},{"name":"Ukraine","area":603550,"population":44429471,"populationGrowthRate":-0.6},{"name":"United Arab Emirates","area":83600,"population":5779760,"populationGrowthRate":2.58},{"name":"United Kingdom","area":243610,"population":64088222,"populationGrowthRate":0.54},{"name":"United States","area":9826675,"population":321368864,"populationGrowthRate":0.78},{"name":"United States Pacific Island Wildlife Refuges","area":22,"population":null,"populationGrowthRate":null},{"name":"Uruguay","area":176215,"population":3341893,"populationGrowthRate":0.27},{"name":"Uzbekistan","area":447400,"population":29199942,"populationGrowthRate":0.93},{"name":"Vanuatu","area":12189,"population":272264,"populationGrowthRate":1.95},{"name":"Venezuela","area":912050,"population":29275460,"populationGrowthRate":1.39},{"name":"Vietnam","area":331210,"population":94348835,"populationGrowthRate":0.97},{"name":"Virgin Islands","area":1910,"population":103574,"populationGrowthRate":-0.59},{"name":"Wake Island","area":7,"population":null,"populationGrowthRate":null},{"name":"Wallis and Futuna","area":142,"population":15613,"populationGrowthRate":0.33},{"name":"West Bank","area":5860,"population":2785366,"populationGrowthRate":1.95},{"name":"Western Sahara","area":266000,"population":570866,"populationGrowthRate":2.82},{"name":"Yemen","area":527968,"population":26737317,"populationGrowthRate":2.47},{"name":"Zambia","area":752618,"population":15066266,"populationGrowthRate":2.88},{"name":"Zimbabwe","area":390757,"population":14229541,"populationGrowthRate":2.21}];
// Logic helpers
// Returns the value at a point in a sorted array. E.g. p = 0.5 -> median
const valueAtPoint = (xs, p) => xs[Math.floor(xs.length * p)];
// Gets the index of an element's quarter in an array
const getQuarter = (xs, x) =>
x === null ? null :
x <= valueAtPoint(xs, 0.75) ? 0 :
x <= valueAtPoint(xs, 0.50) ? 1 :
x <= valueAtPoint(xs, 0.25) ? 2 :
3 ;
// Sort numbers largest first, null last
const numericNullLastSorter = (a, b) =>
a === null ? 1 :
b === null ? -1 :
a < b ? 1 :
a > b ? -1 :
0 ;
// Decorates a sort function to first unwrap property values
const propSorter = (k, f) => (a, b) => f(a[k], b[k]);
// A recursive sort-chainer that keeps on recursing
// until it's either out of sorters, or a sorter has returned
// -1 or 1
const chainSortRec = ([s, ...sorters]) => (a, b) =>
s === undefined ?
0 :
s(a, b) || chainSortRec(sorters)(a, b);
// The same sort-chain but implemented as a loop
const chainSort = (sorters) => (a, b) => {
for (let i = 0; i < sorters.length; i += 1) {
const res = sorters[i](a, b);
if (res) return res;
}
return 0;
};
// The main app logic
// props is an array of strings (keys) we want to sort by, in order
// xs is an array of objects that contain those keys
const sortByProps = (props, xs) => {
const og = Symbol();
const quarterProps = props.slice(0, -1)
const numericProp = props[props.length - 1];
// For every property that sortst by quarter,
// we'll need to sort all items to be able to
// determine the quarter indexes.
const sorts = Object.assign(
{},
...quarterProps.map(k => ({
[k]: xs
.map(x => x[k])
.filter(x => x !== null)
.sort(numericNullLastSorter)
}))
);
// We need a place to link the original entries ot the
// values that determine their sort order
const qIndex = xs.map(x => Object.assign(
// Store a reference to the original item
{ [og]: x },
// Store the numeric value of the last prop
{ [numericProp]: x[numericProp] },
// Store the quarter index of the other props
...quarterProps.map(k => ({
[k]: getQuarter(sorts[k], x[k])
}))
));
// This is our array of sort functions
// Each sort function sorts descending based on a single property
const sorters = props.map(k => propSorter(k, numericNullLastSorter));
return qIndex
// We sort the index based on all sort methods
.sort(chainSort(sorters))
// We return the original objects, not the cached sort values
.map(x => x[og]);
}
// To format our tests:
const topFiveString = props => sortByProps(props, data)
.slice(0, 5)
.map(x => x.name)
.join(", ");
console.log(
`TOP 5s:
by area:
${topFiveString(["area"])}
by area & population:
${topFiveString(["area", "population"])}
by area, population & growth rate:
${topFiveString(["area", "population", "populationGrowthRate"])}`
);