Reverse Vlookup Using Choose Function

[Rick Rothstein]

Maybe not. CHOOSE({1,2},B2:B10,A2:A10) is the same as CHOOSE({2,1},A2:A10,B2:B10) but not the same as CHOOSE({1,2},A2:A10,B2:B10)

I was not referring to the order CHOOSE uses to select from among its arguments (that order is a fixed... 1 refers the second argument, 2 refers to the 3rd argument, etc.), rather, I was referring to the array of cells that CHOOSE presents to VLOOKUP as a result of executing its (implied) array formula. I am guessing you were thinking (originally) CHOOSE({1,2},B2:B10,A2:A10) presents Column B followed by Column A to the VLOOKUP function thereby reversing VLOOKUP's normal order of processing columns, whereas CHOOSE({2,1},A2:A10,B2:B10) presents Column A followed by Column B... all I am saying is that either presents Column A followed by Column B to VLOOKUP (hence, we both used 2 as the "lookup" column), so that there was no need to reverse the numerical order of the array elements in the first argument so long as you make each of them refer to the correct column. Or did I simply misunderstand your original intent?

[Excel Fox]

And the only intent was to tell the reader that even though you pass the LOOKIN arrays in sequential order, you still can reverse its order by reversing the order of numbers in the first argument array of the CHOOSE function.

Which means that if you pass the LOOKIN array in the desired order already, you don't need to reverse the sequential numbers in the index argument of the CHOOSE function.

3rd point. CHOOSE({1,2},A:A,B:B) doesn't pass the element to VLOOKUP as A:B, rather, it passes a combination of multiple arrays having 2 element each, one from A and one from B. The VLOOKUP function actually looks up at these individual combination of arrays.

Which leads to the point that if one were to write VLOOKUP(LookupValue, CHOOSE({2,1},C1:C10,A1:B10),3,0), the formula would return a reference error, because CHOOSE (or Excel) isn't actually combining the array in to a range, but in to multiple arrays