google apps script two columns summary - google-apps-script

Question

I have a google spreadsheet with two columns corresponding to lessons: the first with names of the porfessors (occasionally repeating themselves) and the second with numbers (number of hours). I would like to have as output two columns, the first with the names of the porfessors and the second with the sum of all the hours
I tried with the following code, but it seems to give me back two arrays with the initial colums, as if the condition if (names[names.length-1] == namesColumn[i]) is never met.
What am I doing wrong?
function resumeProfessors() {
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheets()[1];
var namesColumn = sheet.getRange("C4:C31").getValues();
var lessonsColumn = sheet.getRange("G4:G31").getValues();
var names = [];
names.length = 0;
var lessons = [];
lessons.length = 0;
namesColumn.sort();
for (var i = 0; i < namesColumn.length; i++) {
if (names[names.length-1] == namesColumn[i]){
lessons[lessons.length-1] = lessons[lessons.length-1] + lessonsColumn[i];}
else{
sheet.getRange(i+4, 9).setValue(names[names.length-1] + namesColumn[i]);
names[names.length] = namesColumn[i];
lessons[lessons.length] = lessonsColumn[i];
};}
writeResume(names, lessons);
}
Ty

Answer 1

Given your use-case, I'd recommend using a Pivot table or the =QUERY formula.
However, assuming your input sheet looks something like this -
And the expected output is something like this -
You can try the below code -
function myFunction() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var input = ss.getSheetByName('Sheet1');
var output = ss.getSheetByName('Sheet2');
var inputValues = input.getDataRange().getValues();
Logger.log(inputValues)
for (var i = 1; i < inputValues.length; i++) {
var name = inputValues[i][0];
var totalHours = [];
for (var j = 0; j < inputValues.length; j++) {
var hours = inputValues[j][1];
if (name == inputValues[j][0]) {
totalHours.push(inputValues[j][1]);
}
}
var outputValues = output.getDataRange().getValues();
var newEntry = true;
for (var k = 0; k < outputValues.length; k++) {
if (name == outputValues[k][0]) {
newEntry = false;
}
}
if (newEntry) {
output.appendRow([name,totalHours.reduce(function(a, b) {return a + b})]);
}
}
}
Hope this helps.