st: how to flag up obs that are the reverse of other obs?

[David Airey <david.airey@Vanderbilt.Edu>]

> I want to know how to drop some observations.  For example I have the
> following data, the numbers are identifiers:
>
> Original        Fake
> 1                    23
> 14                   235
> 35                    90
> 45                    87
> 87                    45
>
> Now the 4th and 5th pairs are the exact opposite of one another.  I 
> want to
> drop the 5th observation, but I don't know I can use the data to flag 
> up
> such observations so that I can drop it.  Could someone show me the 
> light?
How about a variation on:

replace original = . if original[_n] == fake[_n+1] & original[_n+1] == 
fake[_n]

This would give you:


> Original        Fake
> 1                    23
> 14                   235
> 35                    90
> .                    87
> 87                    45
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