HLOOKUP in R1C1 notation - excel

Question

I'm using Excel VBA to insert an HLOOKUP function at the end of a given row. I've been attempting to use the R1C1 functionality in VBA for inserting the HLOOKUP function, which should appear as follows in Excel:
=HLOOKUP(D2,'DM NYASSOV'!3:34,32,0)
My issue is that I need the HLOOKUP to be dynamic enough that it can reference variables from the same row on which the HLOOKUP function is to be pasted.
Currently my VBA reads as follows:
ThisWorkbook.Sheets(selectTab).Cells(r, 21).FormulaR1C1 = "=HLOOKUP(RC[-17],'DM RC[-19]!'RC[2]:RC[3],RC[3]-RC[2]+1,0)"
RC[-17] references the variable I'm looking for;
RC[-19] is the underlying book/tab identifier;
RC[2] contains the initial row value, and
RC[3] contains the final row reference range.
My main issue is with correctly identifying the dynamic range selection:
'DM NYASSOV'!3:34 / 'DM RC[-19]!'RC[2]:RC[3]
Any pointers are greatly appreciated.

Answer 1

I think you have a few issues here. First is using VBA to dynamically build a formula that then calculates a third value that then gets used in the formula which finally calculates a result. This seems like an unnecessary amount of runaround for a value that can be done with either a formula built on the front end or calculated via VBA in the back end. The second is all the dynamic lookup of it all. It's not so much a problem, but rather a lot to keep track of as you jump through the four hoops. Just the same...
The first parameters of your HLOOKUP can either be a value like "SM1804" or a reference to a cell that contains "SM1804". You can either use VBA to bring this value directly into the formula and save Excel some processing by having to lookup that value at formula processing time:
ThisWorkbook.Sheets(selectTab).Cells(r, 21).FormulaR1C1 = "=HLOOKUP(" & Sheets(selectTab).Cells(r, 21).Offset(0, -17).value & ",'DM RC[-19]!'RC[2]:RC[3],RC[3]-RC[2]+1,0)"
Or you can stick the reference to the cell in there (which is what you are doing now):
ThisWorkbook.Sheets(selectTab).Cells(r, 21).FormulaR1C1 = "=HLOOKUP(RC[-17],'DM RC[-19]!'RC[2]:RC[3],RC[3]-RC[2]+1,0)"
On to the second parameter... I believe you have a sheet name in DM!RC[-19] This is totally OK, but you'll need to use 'Indirect' to get that sheet name into the HLOOKUP formula:
ThisWorkbook.Sheets(selectTab).Cells(r, 21).FormulaR1C1 = "=HLOOKUP(RC[-17],Indirect("'" & DM!RC[-19] & "'!RC[2]:RC[3]"),RC[3]-RC[2]+1,0)"
...this is where things get a little tricky. If, for instance, in DM!RC[-19] you have the sheetname "Sheet1" then indirect is going to return: 'Sheet1'!RC[2]:RC[3] and your HLOOKUP will use that range to do the lookup... Doesn't make a lot of sense to do a HLOOKUP on a range with two cells. So I assume that you have number values in RC[2] and RC[3] there that represent rows. So really the indirect would have to look like:
ThisWorkbook.Sheets(selectTab).Cells(r, 21).FormulaR1C1 = "=HLOOKUP(RC[-17],Indirect("'" & DM!RC[-19] & "'!R" & RC[2] & "C:R" & RC[3] & "C"),RC[3]-RC[2]+1,0)"
Now if your RC[2] has the value "4" and your RC[3] has the value "20" your indirect will return: 'Sheet1'!R4C:R20C and your HLOOKUP will use that value as the range in which it will look up.
You are also doing some math on those values in RC[2] and RC[3], so that's probably all good and doesn't need to be changed. You just need to keep in your head what VBA is going to return as a formula, and then what that formula is going to get from Indirect and then what the resulting HLOOKUP is going to find.
It's a lot to keep track of and may be simplified just by writing the formulas directly in the cell and copying down, or just doing the HLOOKUP functionality directly in VBA.