Count occurrences in array given values of another array

Question

I am writing a script for Google Spreadsheet.

Array 1 have a series of names (more than 50 different names)

John, Pete, Paul, ... Michael

Array 2 is a series of repeated names from those given 50 (more than 10K in total)

Paul, Michael, Pete, John, Paul, Paul, Pete, Michael, Paul, Michael,... Michael

How can I make another Array with the number of occurrences (Array 2) for every given name in Array 1?

Sorting is not possible. Therefore, Array 3 should take into consideration the order of Array 1. In this case, for instance:

1, 2, 3,... 4

I have seen & proved how to make it if order is not important (from Array 2, Array 1 is created with unique names and Array 3 contains their occurrences --> Counting the occurrences of JavaScript array elements), but all my approaches seem to don't work. So far, I have this:

var namesCountArray = [];
namesArray = ss.getRange("CU3:CU" + rows + "").getValues();
namesSerieArray = ss.getRange("DF3:DF" + rows + "").getValues();

for(var i=0; i< namesArray.length; i++) {
    var count = 0;
    for(var i = 0; i < namesSerieArray.length; ++i) {
        if(namesSerieArray[i] == namesArray[i])
            count++;
    }
    namesCountArray.push([count]);
}
ss.getRange("DB3").setValue(namesCountArray);

Answer 1

You need to use a different variable in the second for loop or take it out all together:

for(var i=0; i< namesArray.length; i++) {
  var count = 0;
  for(var i = 0; i < namesSerieArray.length; ++i){
  if(namesSerieArray[i] == namesArray[i])
    count++;
  }

You're going through and checking each pair 1 with 1, 2 with 2, 3 with 3 only. You should do separate variables if you want to check each index pair (1 with 1, 1 with 2 ...). Ex:

for(var i=0; i< namesArray.length; i++) {
  var count = 0;
  for(var j = 0; j < namesSerieArray.length; j++){
  if(namesSerieArray[i] == namesArray[j])
    count++;
  }