如何按多个字段对值进行分组并按特定类型对其进行排序

Question

我正在尝试根据特定字段（值）对对象数组进行分组，然后按特定类型对它们进行排序：var list = [    {value: 'fox', country: 'nl', type: 'animal', priority: 1},  {value: 'fox', country: 'be', type: 'animal', priority: 2},  {value: 'cat', country: 'de', type: 'animal', priority: 3},  {value: 'david', country: 'nl', type: 'human', priority: 4},  {value: 'marc', country: 'be', type: 'human', priority: 5},  {value: 'lola', country: 'de', type: 'human', priority: 6},  {value: 'tiger', country: 'nl', type: 'animal', priority: 7},  {value: 'koala', country: 'be', type: 'animal', priority: 8},  {value: 'tiger', country: 'nl', type: 'animal', priority: 9},];// output/result should be:[  {value: 'fox', countries: ['nl', 'be'], type: 'animal', priority: 1},  {value: 'cat', countries: ['de'], type: 'animal', priority: 2},  {value: 'tiger', countries: ['nl'], type: 'animal', priority: 3},  {value: 'koala', contries: ['be'], type: 'animal', priority: 4},  {value: 'david', contries: ['nl'], type: 'human', priority: 1},  {value: 'marc', contries: ['be'], type: 'human', priority: 2},  {value: 'lola', contries: ['de'], type: 'human', priority: 3},];我正在尝试使用减速器来删除重复的内容，但我无法对国家/地区进行分组list.reduce((accumulator, currentValue, index) => {    const {country, value} = currentValue;  if(!accumulator.some(item => item.value === currentValue.value)) {     accumulator.push({      value: currentValue.value,      countries: [accumulator.country].concat(currentValue.country)    })  }  return accumulator;}, [])

Answer 1

你需要三张通行证

• 按想要的键和值分组

• 对数组进行排序

• 更新prioritiey属性。

function groupBy(data, key, ...values) {

    return Object.values(data.reduce((r, o) => {

        r[o[key]] = r[o[key]] || { ...o, ...Object.fromEntries(values.map(k => [k, []])) };

        values.forEach(k => r[o[key]][k].push(o[k]));

        return r;

    }, {}));

}

var list = [{ value: 'fox', country: 'nl', type: 'animal', priority: 1 }, { value: 'fox', country: 'be', type: 'animal', priority: 2 }, { value: 'cat', country: 'de', type: 'animal', priority: 3 }, { value: 'david', country: 'nl', type: 'human', priority: 4 }, { value: 'marc', country: 'be', type: 'human', priority: 5 }, { value: 'lola', country: 'de', type: 'human', priority: 6 }, { value: 'tiger', country: 'nl', type: 'animal', priority: 7 }, { value: 'koala', country: 'be', type: 'animal', priority: 8 }, { value: 'tiger', country: 'nl', type: 'animal', priority: 9 }],

    result = groupBy(list, 'value', 'country')

        .sort(({ type: a }, { type: b }) => a > b || -(a < b))

        .map((priority => (o, i, { [i - 1]: p }) => {

            if (p && p.type === o.type) ++priority;

            else priority = 1;

            return { ...o, priority };

        })());

console.log(result);

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Answer 2

如果值不存在，您需要检查该值是否存在，否则将新值推送到国家/地区数组。

var list = [

  {    value: 'fox',    country: 'nl',    type: 'animal',    priority: 1  },

  {    value: 'fox',    country: 'be',    type: 'animal',    priority: 2  },

  {    value: 'cat',    country: 'de',    type: 'animal',    priority: 3  },

  {    value: 'david',  country: 'nl',    type: 'human',     priority: 4  },

  {    value: 'marc',   country: 'be',    type: 'human',     priority: 5  },

  {    value: 'lola',   country: 'de',    type: 'human',     priority: 6  },

  {    value: 'tiger',  country: 'nl',    type: 'animal',    priority: 7  },

  {    value: 'koala',  country: 'be',    type: 'animal',    priority: 8  },

  {    value: 'tiger',  country: 'nl',    type: 'animal',    priority: 9  },

];

const l2 = list.reduce((accumulator, currentValue, index) => {

  const {

    country,

    ...value

  } = currentValue;

  const existing = accumulator

    .find(item => item.value === currentValue.value);

  if (existing) {

    const {

      countries

    } = existing;

    countries.push(country);

    existing.countries = Array.from(new Set(countries))

  } else {

    accumulator.push({ ...value,

      countries: [country]

    });

  }

  return accumulator;

}, [])

console.log(l2)

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  max-height: 100% !important;

  top: 0;

}

Answer 3

埃尔达的回答很好。只需在两次推送同一个国家之前添加国家检查。

我还用实际的列表项替换了扩展运算符，以保留它们的结构顺序。

const l2 = list.reduce((accumulator, currentValue) => {

    const {

        value,

        country,

        type,

        priority

    } = currentValue

    const existing = accumulator

        .find(item => item.value === currentValue.value)

    if (existing) {

        if (!(existing.countries.find(addedCountries => addedCountries === currentValue.country))) {

            existing.countries.push(currentValue.country)

        }

    } else {

        accumulator.push({ value,

            countries: [country],

            type,

            priority

        })

    }

    return accumulator

}, [])