Is this close to what you are asking for:
> require(data.table)
> Dt.. <- data.table(Df..)
> R <- Dt..[,
+ list(
+ sum = sum(Volume)
+ , weight = sum(Volume * Mph) / sum(Volume)
+ )
+ , by = list(Min5Break, Day, Hour, Dir)
+ ]
> R
Min5Break Day Hour Dir sum weight
1 1 0 NB 730.8880 32.60224
2 1 0 NB 766.4083 35.88443
3 1 0 SB 776.7592 32.66822
4 1 0 SB 768.0923 33.55988
5 1 0 NB 767.5472 36.00546
6 1 0 NB 767.6600 30.38747
7 1 0 SB 814.9662 31.88483
8 1 0 SB 795.4855 30.91495
9 1 0 NB 828.4439 31.57477
10 1 0 NB 797.7522 29.49832
11 1 0 SB 826.5165 32.74487
12 1 0 SB 824.0942 36.28309
1 2 1 NB 830.0683 29.59320
2 2 1 NB 838.8179 34.59878
3 2 1 SB 877.3518 30.77636
4 2 1 SB 838.9765 30.90577
5 2 1 NB 736.6560 30.54381
6 2 1 NB 772.3622 31.40094
7 2 1 SB 819.2347 29.22674
8 2 1 SB 840.9048 32.59222
9 2 1 NB 818.8383 37.55142
10 2 1 NB 783.8896 32.54565
11 2 1 SB 699.0401 30.76466
12 2 1 SB 773.5594 35.87076
cn Min5Break Day Hour Dir sum weight
>
On Thu, Sep 1, 2011 at 1:11 PM, LCOG1 <jr...@lcog.org> 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.
>
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
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