How to screen out repeated buying/selling signals?

Very simple problem, but I simply can't figure out how.

Say, A1=buy, A2=(space), A3=buy, A4=sell, A5=sell, A6=sell, A7=buy

I want to screen out all the repeated signals, i.e., since I already bought upon A1, I would ignore A3. And sell on A4. After selling on A4, it'd have been sold, and A5/A6 and all subsequent selling signals will be ignored until a buying signal comes to tell me buy again.

So, B1=buy, B2, B3=(space), B4=sell, B5, B6=(space), B7=buy

What formula do I have to put on row B to achieve this result? This single thing would improve the efficiency of my excel technical analysis model a million times, since I now need to screen them out manually, on dozens of stocks, each consisting of dozens of technical models. A million thanks.

Put this in B1:

=A1

and this in B2:

=IF(OR(A2="",A2=LOOKUP("zzz",A$1:A1)),"",A2)

Copy B2 down as far as you need to.

Hope this helps.

Pete

Thanks a lot Pete. Works like magic and that'd really help a lot. The magic power of the LOOKUP function is still beyond my comprehension at this point.
What if the buying and selling signals are written in a language other than English? Like written in two single Chinese characters each representing “buy” and “sell” respectively. What should I put to replace the “zzz”? Thanks again.

I don't know anything about Chinese characters, but the "zzz" in the English version is just a "large" text value, i.e. the last letter of the alphabet repeated three times. Perhaps you can apply this to the Chinese version.

Hope this helps.

Pete

Great help Pete! I found combining the two characters in place of "zzz" perfectly works for me. Simple solution, great results.

Yet in practice now I have another problem. Those signals in row A are not actually plain words “buy”, “sell”, but are formula defining when they would display “buy” and when they would display “sell”. The LOOKUP formula we have works on plain words situation but not formula situations. What else should be put to make that work? It’s great to see the progress and thanks again!

It would help if you attached a sample Excel workbook.

To do this, click on Go Advanced (below the Edit Window) while you are composing a reply, then scroll down to and click on Manage Attachments and the Upload window will open. Click on Browse and navigate to (and double-click) the file icon that you want to attach, then click on Upload and then on Close this Window to return to the Edit window. When you have finished composing your post, click on Submit Post. Don't try to use the Paperclip icon (attachments button), as it doesn't work on this forum.

Hope this helps.

Pete