Hi. My dataset has an id variable and a total amount variable. There are multiple observations per id and within a single id there are sometimes negative numbers of the same positive number in another observation. How do I flag these entries that are merely negatives of each other? For example, in the given table below, I want to flag the first two entries for id 1 and the first and third entry for id 3.
Id Total Amount
1 34
1 -34
1 25
2 13
2 14
3 456
3 43
3 -456
3 765