[英]How to get the difference between 2 Arrays of Date Ranges?
我有2個日期范圍數組,我試圖找出兩者之間的區別。 我們以數字為例:
我有2個范圍[1-7, 9-16]
,我想減去[2-3, 7-9, 14-20]
並得到結果范圍[1-1, 4-6, 10-13]
我被弄得一頭霧水,試圖弄清楚。 當然,我不知道有一個通用的解決方案嗎?
diffDateRangesArray(rangesArray1, rangesArray2) {
//rangesArray = [{startDate, endDate}]
let diffedRanges = [];
rangesArray1.forEach(function(range1){
//loop through rangesArray2 removing from range1
rangesArray2.forEach(function(range2){
// breaks if array returned
// perhaps should always return array and flatten?
range1 = diffDateRanges(range1, range2);
});
diffedRanges.push(range1);
});
//probably should do some sort of union here
return diffedRanges;
}
diffDateRanges(range1, range2) {
//range = {startDate, endDate}
let diffedRange = {};
// if not in range
if(range2.endDate <= range1.startDate || range2.startDate >= range1.endDate){
return range1;
//if envelops range
} else if(range2.endDate >= range1.endDate && range2.startDate <= range1.startDate){
return null;
//if cuts off end of range
} else if(range2.startDate <= range1.endDate && range2.endDate >= range1.endDate){
return {startDate:range1.startDate, endDate: range2.startDate};
// if cuts off start of range
} else if(range2.endDate >= range1.startDate && range2.startDate <= range1.startDate){
return {startDate:range2.endDate, endDate: range1.endDate};
// if inside of range - should better handle arrays
} else if(range2.startDate >= range1.startDate && range2.endDate <= range1.endDate){
return [
{startDate:range1.startDate, endDate: range2.startDate},
{startDate:range2.endDate, endDate: range1.endDate},
];
}
}
如果我正確地理解了您的問題,則可以通過以下步驟完成您想要的工作:
讓我們首先創建一些實用函數:
function range(start, end) {
return [...Array(end - start + 1)].map((_, i) => start + i)
}
function unique(a) {
return Array.from(new Set(a))
}
function immutableSort(arr) {
return arr.concat().sort((a, b) => a - b)
}
Array.prototype.has = function(e) {
return this.indexOf(e) >= 0
}
Object.prototype.isEmpty = function() {
return Object.keys(this).length === 0 && this.constructor === Object
}
function arrayDifference(A, B) {
return A.filter((e) => B.indexOf(e) < 0)
}
現在,讓我們執行一些功能來解決您的特定問題:
function arrayToRangeObjects(A) {
const preparedA = immutableSort(unique(A))
const minA = preparedA[0]
const maxA = preparedA[preparedA.length - 1]
const result = []
let rangeObject = {}
range(minA, maxA).forEach((v) => {
if (!preparedA.has(v)) {
if (rangeObject.hasOwnProperty('start')) {
if (!rangeObject.hasOwnProperty('end')) {
rangeObject.end = rangeObject.start
}
result.push(rangeObject)
}
rangeObject = {}
} else {
if (rangeObject.hasOwnProperty('start')) {
rangeObject.end = v
} else {
rangeObject.start = v
}
}
})
if (!rangeObject.isEmpty()) {
result.push(rangeObject)
}
return result
}
function rangeObjectToRange(rangeObject) {
return range(rangeObject.start, rangeObject.end)
}
function rangeObjectsToRange(A) {
return immutableSort(
unique(
A
.map((rangeObject) => {
return rangeObjectToRange(rangeObject)
})
.reduce((a, b) => {
return a.concat(b)
}, [])
)
)
}
這樣,您的問題的答案是:
function yourAnswer(A, B) {
return arrayToRangeObjects(
arrayDifference(rangeObjectsToRange(A), rangeObjectsToRange(B))
)
}
讓我們測試一下:
const A = [
{
start: 1,
end: 7
},
{
start: 9,
end: 16
}
]
const B = [
{
start: 2,
end: 3
},
{
start: 7,
end: 9
},
{
start: 14,
end: 20
}
]
> yourAnswer(A, B)
[
{
start: 1,
end: 1
},
{
start: 4,
end: 6
},
{
start: 10,
end: 13
}
]
就像個人觀點一樣,我認為您的“范圍對象”數據結構有點難以操作,而且有點不靈活(所有這些麻煩都是為了獲得與范圍集合不重疊的范圍):可能想看看用於存儲范圍的更有效的數據結構 。
因此事實證明這被稱為間隔代數,並且有用於此https://www.npmjs.com/package/qintervals的庫
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.