javascript - 如何获得定期间隔计数

Question

所以我有以下格式的数据

const data = [
  { date: '01-07-2019' },
  { date: '02-07-2019' },
  { date: '03-07-2019' },
  { date: '04-07-2019' },
  { date: '05-07-2019' },
  { date: '06-07-2019' },
  { date: '07-07-2019' },
  { date: '08-07-2019' },
  { date: '09-07-2019' },
  { date: '10-07-2019' },
  { date: '15-07-2019' },
  { date: '16-07-2019' },
  { date: '20-07-2019' },
  { date: '21-07-2019' },
  { date: '22-07-2019' },
  { date: '23-07-2019' }
]

所以我必须计算定期间隔日期。例如日期 { date: '10-07-2019' }, { date: '20-07-2019' } 和 { date: ' 23-07-2019' 它中断了，因此计数应该再次从 1 开始。

const ouput = [{
    startDate: '01-07-2019',
    endDate: '10-07-2019',
    count: 10
}, {
    startDate: '15-07-2019',
    endDate: '16-07-2019',
    count: 2
}, {
    startDate: '20-07-2019',
    endDate: '23-07-2019',
    count: 4
}]

我做到了

const output = Object.values(data.reduce((a, { startDate, endDate }, i) => {
  const startTime = moment(data[i].date)
    const endTime = moment(data[i + 1] && data[i + 1].date)
    if (moment.duration(endTime.diff(startTime)).asDays === 1) {
    a.startDate = startDate
    a.startDate = endDate
  }
  a.count++;
  return a;
}, {}));

但它没有提供我所期望的。请帮忙。

Answer 1

我会使用函数生成器来处理所需的聚合。

下面的代码将循环日期，取一对，检查开始日期是否存在，更新结束日期并在必要时自动生成值。

注释直接在下面的代码中，代码假设初始数组已经按照您提到的示例排序。

作为旁注，您实际上将最后一个日期包括在计数中，而实际上，它应该比您的计数少一天。下面的函数生成器代码中提供了关于此的更多评论。

const data = [
  { date: '01-07-2019' },
  { date: '02-07-2019' },
  { date: '03-07-2019' },
  { date: '04-07-2019' },
  { date: '05-07-2019' },
  { date: '06-07-2019' },
  { date: '07-07-2019' },
  { date: '08-07-2019' },
  { date: '09-07-2019' },
  { date: '10-07-2019' },
  { date: '15-07-2019' },
  { date: '16-07-2019' },
  { date: '20-07-2019' },
  { date: '21-07-2019' },
  { date: '22-07-2019' },
  { date: '23-07-2019' }
];

// Counts intervals of consecutive dates.
function* countIntervals(dates) {
  // declare an initial accumulator.
  let acc = {
    count: 0
  };
  for (let i = 0; i < dates.length; i++) {
    // get the currently looped value and the next one.
    const [curr, next] = [moment(dates[i].date, 'DD-MM-YYYY'), dates[i+1] ? moment(dates[i+1].date, 'DD-MM-YYYY') : null];
    // if the current date and next days are valid and if the difference in days between them is 1..
    if (curr && next && (next.diff(curr, "days") === 1)) {
      // Then keep track of the start date if not set, update the end date and increase the count of days.
      acc.startDate = acc.startDate || dates[i].date, acc.endDate = dates[i+1].date, acc.count++;
    }
    else {
      // otherwise, if the accumulator has a start date, yield the value.
      if (acc && acc.startDate) {
        acc.count++; // <-- comment this if you don't want the last date to be included.
        yield Object.assign({}, acc);
        // and init again the accumulator.
        acc = {
          count: 0
        };
      }
    }
  }
  // if the loop is finished and the progression continued, yield the current accumulator.
  if (acc.startDate) yield acc;
}

// usage...
const intervals = [...countIntervals(data)];
console.log(intervals);

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