如何通过比较具有相同“ID”列的另一列中的值来标记单元格？

Question

I have a sample table like this:

base

I wanted to flag if there is an increase in Output of the same ID compared to the previous Date. Note that the data is only sorted by Date .

Expected output: output

I've been trying to find the correct formula so that it only compares between current output with previous output of the same ID in previous date with INDEX-MATCH functions and had no luck. Thank you for your assistance.

=IF(AND(D2>INDEX($D$2:$D$9, MATCH(C2,$C$2:$C$9,0)-1), C2=INDEX($C$2:$C$9, MATCH(B2,$B$2:$B$9,0)-1)), "Flag", "")

Answer 1

Try the following formula-

=IF(C2>TAKE(TAKE(FILTER($C$2:$C2,$B$2:$B2=B2,0),-2),1),"Flag","")

Answer 2

The following is an array approach. In cell D2 use the following formula:

=LET(A, A2:A9, B, B2:B9, C, C2:C9, MAP(A, B,C, LAMBDA(aa,bb,cc, LET(
  f, FILTER(C, (B=bb) * (A < aa),""), IF(OR(@f="", TAKE(f,-1)>=cc),"", "Flag")))))

Here is the output:

On each MAP iteration we filter Output column ( C ) by ID ( B ) equals to bb and only previous dates. To select filtered the output ( f ) that corresponds to previous date we use: TAKE(f,-1) , ie select the last filtered row (data is sorted by date in ascending order). Then we check for empty condition: the filter result is empty ( @f="" ), ie no result returned under filter condition or the output is not ascending.