How to Find Empty Rows Using Map() in Google Apps Script

Question

I just renew the example and also add the How I want the code to work

I'm quite new with map() function. I want to change the for and if condition to map() because it takes to long for processing a lot of data. Or you guys have any idea to make my code more faster and efficient to work, it can be really helpful.

How I want my code's work:
1. Find the row that have empty value on Column 3 from Table of Data
2. Concate or merge the value of Column 1 and Column 2 from Table of Data
3. Find the same value with the merged value in Table of Source_data
4. If the merged value is same with the value of Column 1 on Table of Source_data, then Get the data of column 2, Column 3, and Column 4
5. Write the data from Table of Source_data (Column 2, Column 3, Column 4) on the Column 3, Column 4, and Column 5 of Table of Data (Result like The Expected Output)

Thank you!

Table of Data:

Column 1	Column 2	Column 3	Column 4	Column 5
lose	data	data1	data2	data3
Second	row
Second	row
Second	row	data4	data5	data6

Table of Source_Data:

Column 1	Column 2	Column 3	Column 4
losedata	data1	data2	data3
Secondrow	data4	data5	data6

Table of Data: (Expected Output)

Column 1	Column 2	Column 3	Column 4	Column 5
lose	data	data1	data2	data3
Second	row	data4	data5	data6
Second	row	data4	data5	data6
Second	row	data4	data5	data6

function main3() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName('Sheet1');
  var data = sheet.getDataRange().getValues();
  var source_file = SpreadsheetApp.openById("").getSheetByName("");
  var source_data = source_file.getRange(2, 1, source_file.getLastRow() - 1, source_file.getLastColumn()).getValues();

  var headerName1 = "Column 1";
  var headerName2 = "Column 2";
  var header = data.shift();
  var header_index1 = header.indexOf(headerName1);
  var header_index2 = header.indexOf(headerName2);

 
  // To find empty row with specific number of column
  for (var i = 1; i < data.length; i++) {
    if (data[i][2] == "") {

      // merge 2 column
      // column 1: lose and column 2: data
      // var concat will generate the merge of those two column -> losedata
      var concat = data.map((row, i) => ([data[i][header_index1] + data[i][header_index2]]));

      // find the same value with the value of merged columns
      // this will find the same data on source_data (Source Spreadsheet) like "losedata"
      var matching = concat.map(row => {
        var row_match = source_data.find(r => r[0] == row[0])
        return row_match ? [row_match[3], row_match[4], row_match[5]] : [null, null, null]
      });
// write the value to the table of Data
   sheet.getRange(2, 3, matching.length, matching[0].length).setValues(matching);
    }
  }

}

Answer 1

As far as I can tell the problem is in setValues() inside the loop. It doesn't matter if the loop is for() or map(). If you want to speed up the script you have to reduce calls to the server. I believe in this case you can process all data on client side as a 2d array and set it on the sheet all at once with just one setValues():

function myFunction() {
  // get the destination sheet and data
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName('Sheet1');
  var [header, ...data] = sheet.getDataRange().getValues();

  // get the source data
  var source_file = SpreadsheetApp.openById('').getSheetByName('');
  var [_, ...src_data] = source_file.getDataRange().getValues();

  // make source object from the source data {col1:[col2, col3, col4], ...}
  var obj = {};
  src_data.forEach(x => obj[x[0]] = x.slice(1));

  // loop through all the data and add cells from the object
  // whenever the object has the key (key is col1 + col2 of current row)
  for (let row in data) {
    var key = data[row][0] + data[row][1];
    if (key in obj) data[row] = [data[row][0], data[row][1], ...obj[key]];
  }

  // make the table from the updated data and set the table on the sheet
  var table = [header, ...data];
  sheet.getDataRange().setValues(table);
}

Data (original):

Source:

Data (results):

Update

It turned out the actual data has another columns.

Data (original):

Source:

Data (results):

The updated code to copy the blue columns from source to the data sheet (based on 'keys' in yellow columns) is here:

function myFunction() {
  // get the destination sheet and data
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName('Sheet1');
  var [header, ...data] = sheet.getDataRange().getValues();

  // get the source data
  var source_file = ss.getSheetByName('Source');
  // var source_file = SpreadsheetApp.openById('').getSheetByName('');
  var [_, ...src_data] = source_file.getDataRange().getValues();

  // make source object from the source data {col1:[col2, col3, col4], ...}
  var obj = {};
  src_data.forEach(x => obj[x[0]] = x.slice(3));

  var headerName1 = "Column 1";
  var headerName2 = "Column 5";
  var header_index1 = header.indexOf(headerName1);
  var header_index2 = header.indexOf(headerName2);

  // loop through all the data and add cells from the object
  // whenever the object has the key (key is col1 + col2 of current row)
  for (let row in data) {
    var key = data[row][header_index1] + data[row][header_index2];
    if (key in obj) data[row] = [...data[row].slice(0,5), ...obj[key]];
  }

  // make the table from the updated data and set the table on the sheet
  var table = [header, ...data];
  sheet.getDataRange().setValues(table);
}

Answer 2

A better way to look for empty cells is using the Range.getNextDataCell(). This will look for the first empty cell. Assuming there are no empty cells in the column it will find the last empty cell. This is the same as Ctrl+[arrow key]. You can also use it to find empty columns by using Direction.NEXT or PREVIOUS.

Actually it's not the empty cell it returns but the boundary cell containing data of the direction you are looking. So be sure and add 1 or subtract 1 if looking UP.

function getEmptyCell() {
  try {
    let spread = SpreadsheetApp.getActiveSpreadsheet();
    let sheet = spread.getSheetByName("Sheet3");
    let column = 1;
    // In these 2 examples cell A6 is empty then A16.  Column B has 20 values, more than A
    // This first example finds the first empty cell starting from the 1st row down
    let row = sheet.getRange(1,column).getNextDataCell(SpreadsheetApp.Direction.DOWN).getRow();
    console.log(row);
    // In this example the first empty cell starting from the last row up.
    row = sheet.getRange(sheet.getLastRow()+1,column).getNextDataCell(SpreadsheetApp.Direction.UP).getRow();
    console.log(row);
  }
  catch(err) {
    Logger.log("Error in getEmptyCell: "+err)
  }
}

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