計算二維陣列中的重復項并創建一個新的二維陣列并用計數擴展它

我有一個帶有幾個值的二維陣列。我想計算這個陣列中的重復項并獲得一個帶有值的新二維陣列，最后是計數

let colors = [
  ['blue', 'green', 5.00, 57],
  ['blue', 'green', 5.00, 57],
  ['yellow', 'green', 8.30, 84],
  ['blue', 'green', 5.00, 57],
  ['orange', 'blue', 7.00, 0],
  ['yellow', 'green', 8.30, 84],
];

function count_duplicate() {
  let counts = []
  for (let i = 0; i < colors.length; i  ) {
    if (counts[colors[i]]) {
      counts[colors[i]]  = 1
    } else {
      counts[colors[i]] = 1
    }
  }
  console.log(counts);
}

count_duplicate();

現在我有這個結果

counts = [blue,green,5,57: 3, yellow,green,8.3,84: 2, orange,blue,7,0: 1]

但我需要這樣的陣列

counts = [[blue,green,5,57,3],
          [yellow,green,8.3,84,2],
          [orange,blue,7,0,1]]

uj5u.com熱心網友回復：

您可以Map在此處使用以實作結果：

let colors = [
  ["blue", "green", 5.0, 57],
  ["blue", "green", 5.0, 57],
  ["yellow", "green", 8.3, 84],
  ["blue", "green", 5.0, 57],
  ["orange", "blue", 7.0, 0],
  ["yellow", "green", 8.3, 84],
];

function count_duplicate() {
  let counts = new Map();

  for (let i = 0; i < colors.length; i  ) {
    const data = counts.get(colors[i].toString());
    if (data) data.count  ;
    else counts.set(colors[i].toString(), { value: colors[i], count: 1 });
  }

  const result = [];
  for (let [, { value, count }] of counts) {
    result.push([...value, count]);
  }
  return result;
}

console.log(count_duplicate());

uj5u.com熱心網友回復：

更改array []為an object {}，為了sub-array(row)輕松操作每個出現的次數，它應該是一個物件而不是一個陣列！和使用Object.entries回圈遍歷它的key(str) and value(times), 并回傳str由逗號和它們出現的時間分割。

let colors = [
  ["blue", "green", 5.0, 57],
  ["blue", "green", 5.0, 57],
  ["yellow", "green", 8.3, 84],
  ["blue", "green", 5.0, 57],
  ["orange", "blue", 7.0, 0],
  ["yellow", "green", 8.3, 84],
];

function count_duplicate() {
  let counts = {};//<-- 
  for (let i = 0; i < colors.length; i  ) {
    if (counts[colors[i]]) {
      counts[colors[i]]  = 1;
    } else {
      counts[colors[i]] = 1;
    }
  }
 console.log(counts); //{ 'blue,green,5,57': 3, 'yellow,green,8.3,84': 2, 'orange,blue,7,0': 1 }
  const res = Object.entries(counts).map((count) => {
    [str, times] = count; //['blue,green,5,57': 3]
    return [...str.split(","), times];//[ 'blue', 'green', '5', '57', 3 ]
  });
  console.log(res);
}
count_duplicate();

結果：

[ [ 'blue', 'green', '5', '57', 3 ],
  [ 'yellow', 'green', '8.3', '84', 2 ],
  [ 'orange', 'blue', '7', '0', 1 ] ]

uj5u.com熱心網友回復：

我不知道花哨的語法，但使用哈希圖應該可以作業，它只是一個 JavaScript 物件。

let colors = [
        ['blue', 'green', 5.00, 57],
        ['blue', 'green', 5.00, 57],
        ['yellow', 'green', 8.30, 84],
        ['blue', 'green', 5.00, 57],
        ['orange', 'blue', 7.00, 0],
        ['yellow', 'green', 8.30, 84],
       
];

const hashmap = {};

colors.forEach(color => {
    const key = JSON.stringify(color);
    if(!hashmap[key]) hashmap[key] = 1;
    else hashmap[key]  ;
    if(hashmap[key] == 1) return color;
});

console.log(hashmap);

const uniqueArray = [];

for(const key in hashmap) 
    uniqueArray.push(JSON.parse(key));

console.log(uniqueArray);

uj5u.com熱心網友回復：

您獲得該輸出是因為您使用的環境會自動將陣列強制轉換為字串。例如，Chrome 和 NodeJS 會這樣做，而 Firefox 則不會。

這是一個簡單的方法，它使用一個物件將資料存盤在鍵/值對中更新的顏色資訊。它使用toString陣列作為鍵，一個陣列作為包含原始陣列的值，以及一個初始化的總數。然后可以使用 提取輸出（所有存盤為物件中的屬性值的陣列）Object.values。

let colors=[["blue","green",5,57],["blue","green",5,57],["yellow","green",8.3,84],["blue","green",5,57],["orange","blue",7,0],["yellow","green",8.3,84]];

const out = {};

colors.forEach(arr => {

  // Create the key from the stringified array
  const key = arr.toString();

  // If the output object doesn't have a
  // property with that key create one with
  // an array built from the array, and setting
  // the total to zero
  out[key] = out[key] ?? [ ...arr, 0 ];

  // Increment the total (the last element)
  out[key][arr.length]  ;

});

// Use Object.values to retrieve
// the updated arrays
console.log(Object.values(out));

附加檔案

• 傳播語法

• Nullish coalescing operator

標籤：javascript

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