ArrayFormula, Google Spreadsheet - google-sheets

Question

This seems to be a simple problem that I cannot get around. I have the following formula (works fine).
=MEDIAN(FILTER('Filtered-Data'!$D$4:$D,'Filtered-Data'!$C$4:$C=B3))
What I want is to use ArrayFormula to get a column wise result for the range B3:B instead of just B3
Can this be done?

Answer 1

First idea was to use Google QUERY function, however it does not support standard SQL SELECT ... WHERE... IN (valA,valB...) clause. However thing you want is achievable with ARRAYFORMULA. The trick is to match appropriately two columns, handle errors, and apply appropriate filtering (multiline for readability):
=MEDIAN(FILTER(Filtered-Data'!$D$4:$D,
ARRAYFORMULA(IF(IFERROR(MATCH
(Filtered-Data'!$D$4:$D,'Filtered-Data'!$C$4:$C=B3:B,0),0)>0,TRUE,FALSE))))
Explanation:
ARRAYFORMULA(MATCH(col1,col2,0)) finds in array first row containing value matching criteria, 0/1 determines whether matching starts from top or bottom. For standalone use, MATCH stops after producing first result. Applying ARRAYFORMULA on MATCH gets us close to what we want - it produces an array of results. However, if item is not matched, error is returned, so you get something like below, in a column:
N/A
2
3
1
3
2
N/A
N/A
N/A
1
3
These N/A stuff will do us no good, since we always want some kind of row number. Here comes IFERROR, which replaces all N\A with good ol' "0": IFERROR(MATCH(col1,col2,0),0)
Google Spreadsheet never counts rows from "0" (it starts from "1", only offsets are zero-based), so this is pretty safe unless your data contains "0" - than change it to anything else safe for your case.
Since FILTER expects in filtering_criteria single column array of booleans or expression that evaluates to array of booleans (https://support.google.com/drive/table/25273?hl=en ) we need to make sure ARRAYFORMULA produces such array of booleans. IF comes in handy - always produces either TRUE or FALSE: IF(IFERROR(MATCH(col1,col2,0)>0,TRUE,FALSE)
Now re-apply ARRAYFORMULA on that stuff, to work on array & render an array result instead of single result: ARRAYFORMULA(IF(IFERROR(MATCH(col1,col2,0)>0,TRUE,FALSE)) and put it inside FILTER... voila, it works.
For reference see: http://productforums.google.com/forum/#!topic/docs/PpnZinkLzQs