使用 ARRAYFORMULA 检测 Google 表格中的重复项

Question

I'm trying to build a Google Sheet that looks like this:

+-------------------+-----------+
|Email              |Duplicate? |
+-------------------+-----------+
|banana@example.com |No         |
|orange@example.com |No         |
|peach@example.com  |No         |
|banana@example.com |Yes        |
|banana@example.com |Yes        |
|apple@example.com  |No         |
|peach@example.com  |Yes        |
+-------------------+-----------+

In my example, the first column is filled in manually with some email addresses. The second column should be a formula that returns Yes if the value has been duplicated previously in the column, and No if it hasn't.

So far, I've trying to use VLOOKUP and INDIRECT inside of ARRAYFORMULA to accomplish this. If I can get that to successfully return a value, then I can build the IF around it to return the strings I want. However, this doesn't work.

=ARRAYFORMULA(VLOOKUP(B2:B, INDIRECT("B1:B" & ROW(B2:B) - 1), 1, FALSE))

I've also tried using COUNTIF , but that doesn't seem to be playing nice with ARRAYFORMULA either.

I'd really appreciate some insight here on what I'm missing. Am I thinking about ARRAYFORMULA wrong? Does INDIRECT not work the way I think it does?

Answer 1

try:

=ARRAYFORMULA(IF(A1:A<>"", IF(
 (COUNTIFS(A1:A, A1:A, ROW(A1:A), "<="&ROW(A1:A))>1)*
 (COUNTIF( A1:A, A1:A)>1), "yes", "no"), ))