I have an array having multiple objects:
[ {col:1} {col:1} {col:1} {col:3} {col:3} {col:9} {col:12} {col:13} ]
I want to update this array such that col having values 1 will remain same while the next value (here 3) should become 2 and then next value(here 9) should become 3 and so on..
O/P:
[ {col:1} {col:1} {col:1} {col:2} {col:2} {col:3} {col:4} {col:5} ]
Please help.
Here is a fairly simple method:
var arr = [ {col:1}, {col:1}, {col:1}, {col:3}, {col:3}, {col:9}, {col:12}, {col:13} ];
var current = 0;
var prevEl = -1;
for (var i = 0; i < arr.length; i++) {
var el = arr[i].col;
arr[i].col = el > prevEl ? ++current : current;
prevEl = el;
}
console.log(arr);You can reduce your array:
var data = [
{ col: 1 }, { col: 1 },
{ col: 1 }, { col: 3 },
{ col: 3 }, { col: 9 },
{ col: 12 }, { col: 13 }
];
var result = data.reduce(function(r, i) {
r.previous !== i.col && r.newValue++;
r.previous = i.col;
r.arr.push({ col: r.newValue });
return r;
}, {arr: [], newValue: 0}).arr;
console.log(result);
I suppose your array is sorted by col, otherwise you need to sort it first.
Should do what is needed. Doesn't rely on any specific order in original array and assumes will always start at 1
var data=[ {col:1} ,{col:1} ,{col:1} ,{col:3} ,{col:3}, {col:9} ,{col:12} ,{col:13} ];
var uniqueValues = data.reduce(function(a,c){
if(a.indexOf(c.col)===-1) {
a.push(c.col);
}
return a;
},[]).sort(function(a,b){
return a-b;
}); // produces [1,3,9,12,13]
var res=data.map(function(item){
// use index of current col value from unique values .. plus one
item.col=uniqueValues.indexOf(item.col) + 1;
return item;
});
document.getElementById('pre').innerHTML = JSON.stringify(res,null,4)<pre id="pre">Edit: if lowest col isn't 1 can still use uniqueValues.indexOf(item.col) + uniqueValues [0]
You could run a for loop to iterate through your array, and have if clauses to check for certain values; say the array object is called myArray:
var myArray = [ {col:1} {col:1} {col:1} {col:3} {col:3} {col:9} {col:12} {col:13} ];
for ( var i = 0; i < myArray.length; i++){
if ( myArray[i] === 3 ){
myArray[i] = 2;
}
// and so on.....
}
myArray[i] is an object. Concept also doesn't adjust based on filling holes in values and is definitely not scalable. Create your own demo will see problems appear then
.col?