Array of arrays with repeated values

Question

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

I have an array of arrays. So, most of the items in the array are the same. The result I want should have only one of each of the arrays plus an extra item that states the number of times the array was repeated.

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

score 1 · Accepted Answer · answered Jul 22 '21 at 13:26

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);

Array of arrays with repeated values

1 Answers1