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創建新的城邦對象

JavaScript

慕哥6287543 2023-09-28 15:22:34

我想將初始數據轉換為所需的結果，我正在努力將城市推送到數組并確保名稱鍵是唯一的。初始數據[ { "city": "Abbeville", "state": "Louisiana" }, { "city": "Aberdeen", "state": "Maryland" }, { "city": "Aberdeen", "state": "Mississippi" }, { "city": "Aberdeen", "state": "South Dakota" }, { "city": "Aberdeen", "state": "Washington" }, { "city": "Abilene", "state": "Texas" }, { "city": "Abilene", "state": "Kansas" }, { "city": "Abingdon", "state": "Virginia" }, { "city": "Abington", "state": "Massachusetts" }, { "city": "Abington", "state": "Massachusetts" },]代碼 let newCityStateObject = cities.map((item, index) => { console.log("item ", item); if (item) { let object = {}; let citiesArray = []; //set state and create empty array if (object[item.state] === undefined) { object.name = item.state; object.cities = [].push(item.city); } else { //key exists so just push to array if (object[item.state]) { object.cities.push(item.city); } } console.log("end ", object); return object; } });我現在的結果[ { state: 'Louisiana', cities: [] }, { state: 'Maryland', cities: [] }, { state: 'Mississippi', cities: [] }, { state: 'South Dakota', cities: [] }, { state: 'Washington', cities: [] }, { state: 'Texas', cities: [] }, { state: 'Kansas', cities: [] }, { state: 'Virginia', cities: [] },]期望的結果[{ "name": "Kentucky", "cities": [ "Louisville/Jefferson County", "Lexington-Fayette", "Bowling Green", "Owensboro", "Covington" ] }, { "name": "Maryland", "cities": [ "Baltimore", "Frederick", "Rockville", "Gaithersburg", "Bowie", "Hagerstown", "Annapolis" ] }]任何幫助/提示或指出解決此問題的正確方向將不勝感激。

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2 回答

翻閱古今

TA貢獻1780條經驗獲得超5個贊

您基本上是按州對城市進行分組。首先，array.map這不是解決此問題的正確方法，因為當您分組時，輸入項的編號可能與輸出項的編號不匹配。array.reduce是更好的選擇。

let newCityStateObject = cities.reduce((acc, item, index) => {

if (item) {

// this object has state as key, and the desired output array’s item as value

const object = acc.obj;

// if state not found, create new record

if (object[item.state] === undefined) {

const record = { name: item.state, cities: [] }

object[item.state] = record;

acc.array.push(record);

}

const record = object[item.state];

record.cities.push(item.city);

}

return acc;

}, { obj: {}, array: [] }).array;

反對回復 2023-09-28

POPMUISE

TA貢獻1765條經驗獲得超5個贊

這是另一種考慮方法：

let newCityStateObject = () => {

const statesArr = Array.from(cities, (item) => item.state);

// Remove state duplications

const filteredStates = [...new Set(statesArr)];

// Initializing the name and cities object and array

let result = filteredStates.map((item) => {

return { name: item, cities: [] };

});

// For each cite item, fetch the city to its corresponding result by state

cities.forEach((item) =>

result

.find((element) => element.name === item.state)

.cities.push(item.city)

);

return result;

}

反對回復 2023-09-28

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創建新的城邦對象

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