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proj1
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