[R] How to preserve date format while aggregating
erich.studerus at bli.uzh.ch
Mon Sep 8 12:38:47 CEST 2008
I have a dataframe in which some subjects appear in more than one row. I
want to extract the subject-rows which have the minimum date per subject. I
tried the following aggregate function.
Unfortunately, the format of the Date-column changes to numeric, when I'm
applying this function. How can I preserve the date format?
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