匹配相同值的十进制数字以推入数组

Question

i have a Srings inside of array

var QNo = ["1.1","1.2","1.3","2.1","2.2","3.1","3.2","3.3","4.1","4.2"];

Need to change QNo in array of objects with matching decimals like this

var result = [["1.1","1.2","1.3"],["2.1","2.2"],["3.1","3.2","3.3"],["4.1","4.2"]];

i hv tried this kind of code

for (var j = 0; j < QNo.length ; j++) {
     if ( QNo[j].match(/.*(?=\.)/g) ) {
      result.push(QNo[j]);
     }
}

After the Match i don't get any idea to push decimals values as object

Answer 1

You can use reduce to go over all the items in the array and group them by their int value using an object where each item will go into the relevant key in that object (the key is based on the int value):

 var QNo = ["1.1","1.2","1.3","2.1","2.2","3.1","3.2","3.3","4.1","4.2"]; var reduced = QNo.reduce((res, item) => { if (res.hasOwnProperty(parseInt(item))) { res[parseInt(item)].push(item) } else { res[parseInt(item)] = [item] } return res; }, {}); console.log(reduced); console.log(Object.values(reduced)); 

Answer 2

You could take the left part of the splitted value and check if the last value is in the same group -- then push the value to the group. If not, then build a new group.

 var qNo = ["1.1", "1.2", "1.3", "2.1", "2.2", "3.1", "3.2", "3.3", "4.1", "4.2"], result = qNo.reduce(function (r, a, i, aa) { function left(a) { return (a || '').split('.')[0]; } if (left(a) === left(aa[i - 1])) { r[r.length - 1].push(a); } else { r.push([a]); } return r; }, []); console.log(result); 

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For unsorted values, you could use a hash table and sort the result later.

 var qNo = ["1.1", "3.1", "1.2", "1.3", "2.1", "3.2", "3.3", "4.1", "2.2", "4.2"], hash = Object.create(null), result = qNo.reduce(function (r, a, i, aa) { function left(a) { return (a || '').split('.')[0]; } var key = left(a); if (!hash[key]) { hash[key] = []; r.push(hash[key]); } hash[key].push(a); return r; }, []); console.log(result); 

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