excel indirect cell reference and index rows - excel

Question

I want to reference the worksheet name and then transpose the totals in row 1 to a column in my summary worksheet.
I have found the following formula, which looks up a worksheet and takes the total, then I can paste this down to look up the row, essentially transposing row H1 to AG1 to column B on my summary worksheet.
=INDEX('201510'!$H$1:$AG$1,ROWS(B$1:B1))
Now I want to replace the direct ref to the worksheet tab to a lookup. So when I type the worksheet name in say row 2, it will give me the monthly totals.
This formula looks up the tab reference in B2 and displays the contents of H1. Where B2 has the worksheet name.
=INDIRECT("'"&$B$2&"'!$H1")
However when I copy this formula down the column, H1 does not change to H2. Furthermore, I need it to transpose vertically to I1.
How can I combine the two formulae?
Thanks,
Andy

Answer 1

You will need to combine the logic of an INDIRECT function with regular Excel referencing. Note that in your final formula, the "'!$H1" is text, meaning Excel doesn't try to compute it until it calculates the value of the cell. ie: it does not compute that what you are typing is a reference, just text.
So, assuming you continue to use the INDIRECT function, you will need to create the address of the final portion dynamically. There are many ways to do this. For example:
=INDIRECT("'"&$B$2&"'!H"&ROW()-1)
This version takes the string of the sheet name from B2, and then adds on the "'!H" as an additional string, and then takes the row as the current row number of the cell above the cell the formula is in. ie: if this formula is in D2, it will look up H1 on the other sheet. This method relies on your formula being in a consistent position within your sheet - if you insert a row above this one, it will change what ROW() calculates as, thus changing the formula.
Another method would be to reference H1 in a way that consistently points there, and also iterates into higher numbers as you drag down the formula. This method may be more useful for your purposes, as it also teaches another function:
=INDIRECT(ADDRESS(ROW(H1),COLUMN(H1),,1,$B$2))
Note that the ADDRESS function creates a string which shows the way a direct reference to a specific cell would. with the arguments I have above, it picks up the row number of H1 [iterating down, as there are no $ in front of the 1], the column number of H1 [iterating to the right, as there is no $ in front of the H], and the sheet name from $B$2.