google apps script - creating 2 dimension arrays

Question

I am new to JS and need some basic help:

I have a spreadsheet which has a square matrix of data.

I can read these data as follows:

  var freqArr     = new Array(new Array());
  var freqSheet   = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("freq");
  var freqRows    = freqSheet.getDataRange();
  var freqNumRows = freqRows.getNumRows();
  freqArr = freqSheet.getRange(2, 2, freqNumRows, freqNumRows).getValues();

I now want to create a an array in memory similar to the one I have read from the sheet

 var tempArr = new Array(new Array());
  for (var i = 0; i <= 3; i++) {
    for (var j = 0; j <= 3; j++) {        
      tempArr [i][j] = freqArr[i][j] ;
    }
  }

As soon as j incs from 0 to 1 and I try to store anything in tempArr [i][j] I get an error "TypeError: Cannot set property "0.0" of undefined to "xxx"

I have tried every combination of creating tempArr that I can think of plus a few more.

Answer 1

Someone much smarter than myself could probably help you write this better, but the way it looks to me is that you want to create tempArr as the main array, which would have 2 arrays inside of it.

Inside of each of those arrays are values, so:

// result: tempArr = [[1,2],[4,5]]
tempArr = [] // or new Array
for (var i = 0; i <= 3; i++) {
  tempArr[i] = [];
  for (var j = 0; j <= 3; j++) {        
    tempArr[i].push(freqArr[i][j]);
  }
}

You create your first main array in tempArr, within your for, each time you loop through, tempArr[i] is created as an array, and inside of the second for, you want to push the value of freqArr to the inner array.

UPDATE Had a space in tempArr[i] that would've caused it to not work for sure. Sorry!