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2011 Mar 02
2
how to simplify a data.frame and add the counts of duplicate rows as a new column
Hello List, I would like to simplify a data.frame like this columnA columnB user10 proj12 user10 proj19 user10 proj12 into something like: columnA columnB columnC user10 proj12 2 user10 proj19 1 I know unique() can simplify the data.frame, but how to count and store the duplicates? thanks in advance for any help. best regards, Simone