I would suggest using a 'for' loop rather than an apply function. The advantage is that you will probably understand the loop that you write, and it will run in roughly the same amount of time as a complicated call to an apply function that you don't understand.
On 01/09/2011 18:11, LCOG1 wrote:
Hi guys, I have a crap load of data to parse and have enjoyed creating a script that takes this data and creates a number of useful graphics for our area. I am unable to figure out one summary though and its all cause I dont fully understand the apply family of functions. Consider the following: #Create data Df..<-rbind(data.frame(Id=1:1008,Dir=rep(c("NB","NB","SB","SB"),252),Mph=runif(1008,0,65), Volume=runif(1008,0,19),Hour=rep(00,1008),Min5Break=rep(1:12,84),Day=rep(1,1008)), data.frame(Id=2009:2016,Dir=rep(c("NB","NB","SB","SB"),252),Mph=runif(1008,0,65), Volume=runif(1008,0,19),Hour=rep(01,1008),Min5Break=rep(1:12,84),Day=rep(2,1008))) #Example calc Results_<-list() #Sum Volume by 5 minute break by Day by Direction Results_$FiveMin.Direction<-tapply(Df..$Volume,list(Df..$Min5Break,Df..$Day,Df..$Hour,Df..$Dir),sum) The data is a snap shot of what im working with and I am trying to get to something similar to the last line where the volumes are summed. What i want to do is to do a weighted average for the speed by 5 minute break. So for all the speeds and volumes in a given hour of 5 minute break(12 per hour), i would want to sum(Volumes[1:12]*Speed[1:12]) / sum(Volumes[1:12] The output resembling the one from the above but having these weighted values. I am assuming the sum function in the above would be replaced by a function doing the calculation but I am still not sure how to do this using apply functions, so perhaps this isnt the best option. Hope this is clear and hope you guys(and of course ladies) can offer some guidance. Cheers, Josh -- View this message in context: http://r.789695.n4.nabble.com/Oh-apply-functions-how-you-confuse-me-tp3784212p3784212.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
-- Patrick Burns pbu...@pburns.seanet.com twitter: @portfolioprobe http://www.portfolioprobe.com/blog http://www.burns-stat.com (home of 'Some hints for the R beginner' and 'The R Inferno') ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.