计算和删除嵌套数组中的多个元素

Question

this is the structure of my array:

arrayParent = [numbers, counter];

numbers = [1,1,1,2,4,5];
counter = [];

what I want to do is counting multiple elements in "numbers" and pushing to "counter" while deleting in the first, in the end it should look like this:

numbers = [1,2,4,5];
counter = [3,1,1,1];

I tried this ( and many many other versions):

for(var y =0; y < arrayParent.length; y++){
 for(var x = 0; x < arrayParent[y].numbers.length; x++){
    var co = 1;
    for(var z = x+1; z < arrayParent[y].numbers.length; z++){
      if(arrayParent[y].numbers[x] == arrayParent[y].ans[z]){
          co++;
          arrayParent[y].numbers.splice(z);
          arrayParent[y].counter[x] = co;
       }
     }
   }
}

The result I got:

numbers = [1,2,4,5];
counter = [3,,,];

Any ideas how to solve?

Answer 1

you can try something like:

 let numbers = [1,1,1,2,4,5]; let counter = []; const tmp = numbers.reduce((res, curr) => ({ ...res, [curr]: (res[curr] || 0) + 1 }), {}); numbers = Object.keys(tmp).map(Number); counter = Object.values(tmp); console.log(numbers, counter); 

so, I created a counter object where keys are distinct numbers and values are their counter

As @nikhil correctly noticed this method will not preserve numbers order, to preserve it, just change JS object to JS Map, the logic is the same:

 let numbers = [1,1,1,2,5, 4]; let counter = []; const tmp = numbers.reduce((res, curr) => res.set(curr, (res.get(curr) || 0) + 1), new Map()); numbers = [...tmp.keys()]; counter = [...tmp.values()]; console.log(numbers, counter); 

Answer 2

You can try following

 let arrayParent = {numbers : [1,1,1,2,4,5], counter : []}; // This will ensure that the order of elements is same as in the array let order = []; // Create an object with key as `number` and counts as its value let map = arrayParent.numbers.reduce((a,c) => { if(a[c]) a[c]++; else {a[c] = 1; order.push(c); } return a; }, new Map()); // Set the value of order in numbers arrayParent.numbers = order; // Set the counts in counter order.forEach(o => arrayParent.counter.push(map[o])); console.log(arrayParent);