具有重复值的数组数组

Question

    let array = [
       ["7", "s"],
       ["7", "s"],
       ["6", "d"],
       ["5", "f"],
       ["5", "f"],
       ["5", "f"],
       ["5", "f"],
       ["5", "f"]
    ]

我有一个数组。因此，数组中的大多数项目都是相同的。我想要的结果应该只有每个数组中的一个加上一个额外的项目，说明数组重复的次数。

      //The new third value in the array is the number of times it was repeated.
    [
       ["7", "s", 2],
       ["6", "d", 1],
       ["5", "f", 5]
    ]

Answer 1

let array = [
  ["7", "s"],
  ["7", "s"],
  ["6", "d"],
  ["5", "f"],
  ["5", "f"],
  ["5", "f"],
  ["5", "f"],
  ["5", "f"]
];

let objArrayCount = array.reduce((acc, [number, letter]) => ({
    ...acc,
    [number]: {
      ...acc[number],
      [letter]: acc[number] && acc[number][letter] ? acc[number][letter] + 1 : 1
    }
}), {});

reducedArray = Object.entries(objArrayCount).reduce((acc, [number, letterFrequencyObj]) => [...acc, ...Object.entries(letterFrequencyObj).map(([letter, frequency]) => [number, letter,frequency])],[]);

console.log(reducedArray);

具有重复值的数组数组

Array of arrays with repeated values

javascript

arrays

reduce