If you only care about the sum of CONVUNIT by each TRIPID then you can use tapply i.e.:
step4<-data.frame(TRIPID=rep(c(111,222,333),3),CONVUNIT=rpois(9,40)) result<-tapply(step4$CONVUNIT,INDEX=step4$TRIPID,FUN=sum) result 111 222 333 115 107 123 Is this what you wanted to do? I can't think of anything faster than tapply for your problem. I hope this helps Francisco >From: "Guenther, Cameron" <[EMAIL PROTECTED]> >To: <r-help@stat.math.ethz.ch> >Subject: [R] Unique? >Date: Wed, 10 May 2006 17:02:33 -0400 > > >Hello, >I have sample data set that looks like: > >YEAR MONTH DAY CONTINUE SPL TIMEFISH >TIMEUNIT AREA COUNTY DEPTH DEPUNIT GEAR TRIPID >CONVUNIT >1992 1 26 1 SP0073928 8 >H 7 25 4 NA 1000000 >02163399054 161 >1992 1 26 1 SP0073928 8 >H 7 25 4 NA 1000000 >02163399054 8 >1992 1 26 2 SP0004228 8 >H 7 25 4 NA 1000000 >02163399054 161 >1992 1 26 2 SP0004228 8 >H 7 25 4 NA 1000000 >02163399054 8 >1992 1 25 NA SP0052652 8 >H 7 25 4 NA 1000000 >02163399057 85 >1992 1 26 NA SP0037940 8 >H 7 25 4 NA 1000000 >02163399058 70 >1992 1 27 NA SP0072357 8 >H 7 25 4 NA 1000000 >02163399059 15 >1992 1 27 NA SP0072357 8 >H 7 25 4 NA 1000000 >02163399059 20 >1992 1 27 NA SP0026324 8 >H 7 25 4 NA 1000000 >02163399060 8 >1992 1 28 1 SP0072357 8 >H 7 25 4 NA 1000000 >02163399062 200 > >How can I use unique to extract the rows that have repeated tripid's >only, not a unique value for each variable but only for TRIPID. I then >want to condense the unique values by summing the CONVUNIT for each >unique value of TRIPID. I posted a similar question last week and >received a sufficient answer of how to do this without using uniqe. The >solution below worked just fine on this sample data set but the full >data set has 446,000 rows of data and my computer and R simply cannot >handle this follwing code on data this large. > >conds<-by(Step4,Step4$TRIPID,function(x) >replace(x[1,],"CONVUNIT",sum(x$CONVUNIT))) >Step5<-do.call(rbind,conds) > >Thank you, > >Cameron Guenther, Ph.D. >Associate Research Scientist >FWC/FWRI, Marine Fisheries Research >100 8th Avenue S.E. >St. Petersburg, FL 33701 >(727)896-8626 Ext. 4305 >[EMAIL PROTECTED] > >______________________________________________ >R-help@stat.math.ethz.ch mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! >http://www.R-project.org/posting-guide.html ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
