Dear list,

I have this dataframe:
> names(events)
 [1] "EID"    "X"      "Y"      "trip"   "tow"    "catch"  "effort" "depth" 
 [9] "season" 
Where some of my unique ID "EID" appears more than once in 162 cases.

> length(events$EID)-length(unique(events$EID))
[1] 162
I would like to combined each replicate EID together and sum their "catch". I've been trying a few things with the plyr package... but can't find a rather straightforward command.

Any tips would be much appreciated! Thank you very much!



Aurelie Cosandey-Godin
Ph.D. student, Department of Biology
Industrial Graduate Fellow, WWF-Canada
Dalhousie University | Email: godina@dal.ca
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