Google-sheets – Regex compare two strings

The name and concept of this function comes from Kronecker delta, and it is used for the same reason as it's used in mathematics and engineering: to include equality conditions into algebraic expressions. Excel had this function for a while; the old version of Google Sheets did not, which was noticed. So, if nothing else, better compatibility with Excel is a reason enough to add this function.

As an example, it can be used for things like "the number of places where the numbers in columns A and B agree":

=sum(arrayformula(delta(A1:A,B1:B)))

Of course there are other ways to do the same, like countif: the point of delta is that one could have it in a complex algebraic expression.

The above doesn't quite work with eq: the formula =sum(arrayformula(eq(A1:A,B1:B))) throws an error. One can get around it with =sum(arrayformula(1*eq(A1:A,B1:B))) by converting boolean to integer.

Here is a solution. I didn't include shuffleArray here because it stays exactly the same. shuffleSheet shuffles the range A1:A25 of whatever sheet it is given as a parameter; this is a much better approach than writing 6 nearly identical functions for 6 sheets.

The main function is repeatShuffling. It shuffles every sheet with the name listed in the array sheetNames. It also takes a note of A1 values after shuffling. If the A1 value of the first-named sheet is equal to A1 value elsewhere, the function repeatShuffling is invoked again.

function repeatShuffling() {
  var ss = SpreadsheetApp.getActiveSpreadsheet(); 
  var sheetNames = ["Sheet1", "Sheet2", "Sheet3", "Sheet4", "Sheet5", "Sheet6"];
  var a1values = Array(6);
  for (var i = 0; i < sheetNames.length; i++) {
    var sheet = ss.getSheetByName(sheetNames[i]); 
    shuffleSheet(sheet);
    a1values[i] = sheet.getRange("A1").getValue();
  }
  if (a1values.slice(1).indexOf(a1values[0]) != -1) {
    repeatShuffling(); 
  }  
}

function shuffleSheet(sheet) {   
  var range = sheet.getRange("A1:A25");
  range.setValues(shuffleArray(range.getValues()));
}