Sort the array by unique ID and retrieve the object with the first and last index

Question

Sort the array by unique ID and retrieve the object with the first and last index

I am working with an array that looks like this:

[{
    "res": [ '123', 'One', '20210318' ]
}, {
    "res": [ '123', 'One', '20210319' ]
}, {
    "res": [ '123', 'One', '20210320' ]
}, {
    "res"': [ '123', 'One', '20210321' ]
},{
    "res"': [ '456', 'Two', '20210401' ]
},{
    "res"": [ '456', 'Two', '20210402' ]
},{
    "res": [ '456', 'Two', '20210403' ]
},{
    "res": [ '456', 'Two', '20210404' ]
}]

My goal is to extract the following unique values from the array:

[{ 
    "res": [ '123', 'One', '20210318' ]
 }, {
    "res": [ '123", "One", "20210321' ]
 },{
    "res": [ '456', 'Two', '20210401' ]
    },{
    "res": [ '456', 'Two', '20210404' ]
}]

This means finding the first occurrence of unique value "20210318" for "One" and the last index unique value "20210321", and for "Two" finding the first unique value as "20210401" and the last index unique value as "20210404"

So far, I have successfully filtered the array by their unique IDs and obtained only two results - the first unique occurrence of "One" and the first unique occurrence of "Two"

  const getFilteredArray = array.filter((v,i,a)=> {

    const getFilter = a.findIndex( t => {
      return t.res[0] === v.res[0]
    }) === i;

    return getFilter;
  })

javascript arrays

Answer 1

Answer №1

Here lies a potential solution, perhaps not the optimal one.

let groupedData = array.reduce((acc, {result: [key1, key2, value]}) => {
    acc[key2] = acc[key2] || {};
    acc[key2].key1 = key1;
    if (acc[key2].min == null || acc[key2].min > value) acc[key2].min = value;
    if (acc[key2].max == null || acc[key2].max < value) acc[key2].max = value;
    return acc;
}, {});
Object.keys(groupedData).reduce((acc, k) => {
    const val = groupedData[k];
    acc.push({result: [val.key1, k, val.min]});
    acc.push({result: [val.key1, k, val.max]});
    return acc;
}, []);

Answer 2

Here lies a potential solution, perhaps not the optimal one.

let groupedData = array.reduce((acc, {result: [key1, key2, value]}) => {
    acc[key2] = acc[key2] || {};
    acc[key2].key1 = key1;
    if (acc[key2].min == null || acc[key2].min > value) acc[key2].min = value;
    if (acc[key2].max == null || acc[key2].max < value) acc[key2].max = value;
    return acc;
}, {});
Object.keys(groupedData).reduce((acc, k) => {
    const val = groupedData[k];
    acc.push({result: [val.key1, k, val.min]});
    acc.push({result: [val.key1, k, val.max]});
    return acc;
}, []);

Sort the array by unique ID and retrieve the object with the first and last index

Answer №1

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