Reordering Array Of Objects Into Nested Objects

How do I reorder an array of objects [ {'2007': rank, '2008': rank, 'Class': 'label 1'}, {'2007': rank, '2008': rank, 'Class': 'label 2'}, ... ] into a nested object such as:

Solution 1:

It seems that your requirement is to transpose the table and index by Class:

• call the input "table"
• call every element of the array "row"
• for every year that is a key in at least one row, except the key Class
  • make year a key in output, mapping to the object:
    • each key in output[year] is the value class of Class in some row, mapping to the value:
      • output[year][class] = input.find("Class",class)[year]

This is one possible implementation:

 var input = [ {"2007": rank, "2008": rank, "Class": "label 1"}, 
               {"2007": rank, "2008": rank, "Class": "label 2"} ]
 //////////
 var yr, i;
 var output = {};
 for(i=0; i<input.length; i++){
   var row = input[i];
   for(yr in row){
     output[yr] = output[yr] || {};
     output[yr][row.Class] = row[yr];
   }
 }
 //////////////return output;

test: http://jsfiddle.net/aT5YG/1

If multiple rows have the same Class, the later rows overwrite the previous rows. If the nput was jagged, the output will be jagged.