Google Sheets Custom Formula Sometimes Works Sometimes Doesn't - google-apps-script

Question

I have a spreadsheet in which I developed a custom function called RawVal:
function RawVal(BlockName) {
try {
var rawVal = 1;
var thiSheet = SpreadsheetApp.getActiveSheet();
var BlockRow = thiSheet.getRange("C:C").getValues().map(function(row) {return row[0];}).indexOf(BlockName);
if (BlockRow > -1) {
var baseVal = thiSheet.getRange("B" + (BlockRow+1)).getValue();
var ingVal = thiSheet.getRange("D" + (BlockRow+1)).getValue();
rawVal = Math.max(baseVal, ingVal);
Logger.log(BlockName+": base="+baseVal+"; ing="+ingVal+"; max="+rawVal);
}
return rawVal;
}
catch (e) {
Logger.log('RawVal yielded an error for " + Blockname + ": ' + e);
}
}
While the function is long, the intent is to replace a moderately sized function from having to be typed in on each row such as:
=if(sumif(C:C,"Emerald Block",D:D)=0,sumif(C:C,"Emerald Block",B:B),sumif(C:C,"Emerald Block",D:D))
The problem is sometimes it works and sometimes it just doesn't. And it doesn't seem to be related to the content. A cell that worked previously may display #NUM and have the error "Result was not a number". But if I delete it and retype it (but oddly not paste the formula), most of the time it will calculate correctly. Note: it is NOT stuck at "Loading", it is actually throwing an error.
Debug logs haven't been useful - and the inconsistency is driving me crazy. What have I done wrong?
EDIT: I replaced the instances of console.log with Logger.log - the cells calculated correctly for 6 hours and now have the #NUM error again.

Answer 1

It seems that your custom function is used in many places (on each row of the sheet). This and the fact that they stop working after a while points to excessive computational time that Google eventually refuse to provide. Try to follow their optimization suggestion and replace multiple custom functions with one function that processes an array and returns an array. Here is how it could work:
function RawVal(array) {
var thiSheet = SpreadsheetApp.getActiveSheet();
var valuesC = thiSheet.getRange("C:C").getValues().map(function(row) {return row[0];});
var valuesBD = thiSheet.getRange("B:D").getValues();
var output = array.map(function(row) {
var rawVal = 1;
var blockRow = valuesC.indexOf(row[0]);
if (blockRow > -1) {
var baseVal = valuesBD[blockRow][0];
var ingVal = valuesBD[blockRow][2];
rawVal = Math.max(baseVal, ingVal);
}
return [rawVal];
}
return output;
}
You'd use this function as =RawVal(E2:E100), for example. The argument is passed as a double array of values, and the output is a double array too.
Also, when using ranges like "C:C", consider whether the sheet has a lot of empty rows under the data: it's not unusual to see a sheet with 20000 empty rows that pointlessly get searched over by functions like that.
Alternative: use built-in functions
It seems that your custom function is mostly a re-implementation of existing =vlookup. For example,
=arrayformula(iferror(vlookup(H:H, {C:C, B:B}, 2, false), 1))
looks up all entries in H in column C, and returns the corresponding values in column B; one formula does this for all rows (and it returns 1 when there is no match). You could have another such for column D, and then another arrayformula to take elementwise maximum of those two columns (see Take element-wise maximum of two columns with an array formula for the latter). The intermediate columns can be hidden from the view.