I did some searching on this and came across this post.
However, this solution uses an onEdit() trigger. I would like to see a solution that uses a formula approach, so in the OP's example from that post, the formula would be like so:
=setcolor( if(A1=1,true,false), RGB(255,255,0) )
How can I create a formula that does this?
Google Sheets could be expanded to implement "a formula approach" for certain tasks. This is called "custom functions".
Custom functions should only be used to display values, so they should not be used to set the conditional formating directly. Instead use the conditional formatting built-in feature.
References
In new Google Sheets, under Format, Conditional formatting..., for Custom formula is use =A1=1, choose you formatting and for Range use B1:B7 if you want the same as the post now linked to in your question.
It is not possible to use formulas for conditional formatting based on this Google Groups Discussion.
This is another non-ideal work-around, but what I did was added a certain number of spaces to the end of the cell needing formatting based on the conditions I wanted, then did conditional formatting based on spaces.
Ex: Column A = First Name, Column C = First Name, Column E = Some Number
So what I want is if E > 50, make column A Blue, If E < 0 make column A Red.
First I type the data that I want in Column A into Column C. {Example: "Fred"}
Column A (row 2) then gets the following formula: =If(E2 > 50, C2 & " ",If(E2 < 0, C2 & " ", C2)) {Example: "Fred", "Fred ", or "Fred "}
Put Conditional formatting on Column A: When Text Contains " " make text blue. When Text Contains " " make text red.
Hide Column C.
Again, not ideal, and you have to use more spaces than the data contains (so if you need to have a space in Column C {example "Firstname Lastname"}, use 2 and 3 spaces for the conditional formatting). But it gets the job done and remains relatively transparent.
This is how I do it.. My example i want column C to turn black when column A says "Advert"
I thought of a way to make the columns in C in Google Docs turn black automatically when you type "ADVERT" in Column A. This has stumped me in the past, as unlike Excel, Google Docs doesn't allow color alteration of cells based on formulas from another cell, only its own using conditional formatting.
However, by using the conditional formatting on desired cell (Column C in this case)
is equal to ADVERT then background = BLACK.
# (Translation: if cell C has the word ADVERT, then paint that Cell in C black)
so far not much use as we type ADVERT in A, but bear with me.
Then by using this formula in column C
if (A41="ADVERT","ADVERT","") on that column
#translation: if Cell A41 says ADVERT then print the word Advert in this column, or if not print nothing.
Then the word "Advert" will appear in column C if Column A has that word. That added to the single cell conditional formatting we added at the start of this geek fest, it will see the word ADVERT in its cell and then paint it black (the word advert will not show as its black on black. Doesn't save us much time, but its nice to know such things are possible.
