search for: tp1566260p1566801

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2010 Feb 23
4
First. Last. Data row selection
I am in the process of switching from SAS over to R. I am working on very large CSV datasets that contain vehicle information. As I am processing the data, I need to select the first (or sometimes the second) record (by date) for any records that have the same license plate number. In SAS, there is a function called 'first.' that can be used on sorted datasets to pull out those first