The plyr package is very helpful for this: library(plyr) ddply(x ,.(myweek), summarize, m1=weighted.mean(var1,myweight), m2=weighted.mean(var2,myweight)) -- View this message in context: http://r.789695.n4.nabble.com/weighted-mean-by-week-tp4636814p4636816.html Sent from the R help mailing list archive at Nabble.com.
Thanks a lot, David. Indeed, it's much shorter. Unfortunately, in my real task I am dozens and dozens of variables like var1 and var2 so that manually specifying things like in "m1=weighted.mean(var1,myweight)" would take a lot of code and a very long time. Dimitri On Tue, Jul 17, 2012 at 6:34 PM, David Freedman <dxf1 <at> cdc.gov> wrote: > The plyr package is very helpful for this: > > library(plyr) > ddply(x ,.(myweek), summarize, m1=weighted.mean(var1,myweight), > m2=weighted.mean(var2,myweight)) > > > -- > View this message in context: http://r.789695.n4.nabble.com/weighted-mean-by-week-tp4636814p4636816.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help <at> 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. -- -- Dimitri Liakhovitski marketfusionanalytics.com(Continue reading)
If there are many variables, I'd then suggest the data.table package:
library(data.table)
dt=data.table(x)
dt[,lapply(.SD, function(x)weighted.mean(x,myweight)), keyby=c('group',
'myweek')]
The '.SD' is an abbreviation for all the variables in the data table
(excluding the grouping variables). There's an .SDcols= 'variables of
interest' option if you want to limit the dozens of variables to only some
of them. Or, in the data.table(x) statement, you could limit the created
data table to only the variables your interested in.
As an added benefit, the data.table approach is amazingly fast (particularly
when there are numerous grouping categories)
--
View this message in context: http://r.789695.n4.nabble.com/weighted-mean-by-week-tp4636814p4636825.html
Sent from the R help mailing list archive at Nabble.com.
David, many thanks.
Did something get ommitted from your line?:
ddply(x ,.(myweek), summarize, m1=weighted.mean(var1,myweight),
m2=weighted.mean(var2,myweight))
Because it just reproduces x - in a somewhat different order...
Thank you!
Dimitri
On Tue, Jul 17, 2012 at 9:22 PM, David Freedman <dxf1 <at> cdc.gov> wrote:
> If there are many variables, I'd then suggest the data.table package:
>
> library(data.table)
> dt=data.table(x)
> dt[,lapply(.SD, function(x)weighted.mean(x,myweight)), keyby=c('group',
> 'myweek')]
>
> The '.SD' is an abbreviation for all the variables in the data table
> (excluding the grouping variables). There's an .SDcols= 'variables of
> interest' option if you want to limit the dozens of variables to only some
> of them. Or, in the data.table(x) statement, you could limit the created
> data table to only the variables your interested in.
>
> As an added benefit, the data.table approach is amazingly fast (particularly
> when there are numerous grouping categories)
>
>
> --
(Continue reading)
Honestly, I wasn't sure what you wanted to do with 'group'. Here it is with the 'group' variable deleted library(data.table) dt=data.table(x[,-1]) dt[,lapply(.SD, function(x)weighted.mean(x,myweight)), keyby='myweek'] -- View this message in context: http://r.789695.n4.nabble.com/weighted-mean-by-week-tp4636814p4636828.html Sent from the R help mailing list archive at Nabble.com.
David, thanks a lot! I tried x[-1] myself but forgot to delete 'group' from the keyby statement - this explains why it did not work for me. This is amazing - just 2 lines instead of my many-many. Great learning! Dimitri On Tue, Jul 17, 2012 at 10:49 PM, David Freedman <dxf1 <at> cdc.gov> wrote: > Honestly, I wasn't sure what you wanted to do with 'group'. Here it is with > the 'group' variable deleted > > library(data.table) > dt=data.table(x[,-1]) > dt[,lapply(.SD, function(x)weighted.mean(x,myweight)), keyby='myweek'] > > > > > -- > View this message in context: http://r.789695.n4.nabble.com/weighted-mean-by-week-tp4636814p4636828.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help <at> 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. -- -- Dimitri Liakhovitski(Continue reading)
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