R help - Mar 2011 - summing values by week - based on daily dates - but with some dates missing

Dear everybody,

I have the following challenge. I have a data set with 2 subgroups,
dates (days), and corresponding values (see example code below).
Within each subgroup: I need to aggregate (sum) the values by week -
for weeks that start on a Monday (for example, 2008-12-29 was a
Monday).
I find it difficult because I have missing dates in my data - so that
sometimes I don't even have the date for some Mondays. So, I can't
write a proper loop.
I want my output to look something like this:
group   dates   value
group.1 2008-12-29  3.0937
group.1 2009-01-05  3.8833
group.1 2009-01-12  1.362
...
group.2 2008-12-29  2.250
group.2 2009-01-05  1.4057
group.2 2009-01-12  3.4411
...

Thanks a lot for your suggestions! The code is below:
Dimitri

### Creating example data set:
mydates<-rep(seq(as.Date("2008-12-29"), length = 43, by =
"day"),2)
myfactor<-c(rep("group.1",43),rep("group.2",43))
set.seed(123)
myvalues<-runif(86,0,1)
myframe<-data.frame(dates=mydates,group=myfactor,value=myvalues)
(myframe)
dim(myframe)

## Removing same rows (dates) unsystematically:
set.seed(123)
removed.group1<-sample(1:43,size=11,replace=F)
set.seed(456)
removed.group2<-sample(44:86,size=11,replace=F)
to.remove<-c(removed.group1,removed.group2);length(to.remove)
to.remove<-to.remove[order(to.remove)]
myframe<-myframe[-to.remove,]
(myframe)



-- 
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com

Hi,

How about something like:

sum.by.day <- function(ff) {
  by.day <- split(ff$value,weekdays(ff$dates))
  lapply(by.day,sum)
}

by.grp <- split(myframe,myframe$group)

lapply(by.grp,sum.by.day) 


Martyn

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Dimitri Liakhovitski
Sent: 30 March 2011 15:23
To: r-help
Subject: [R] summing values by week - based on daily dates - but with
somedates missing

Dear everybody,

I have the following challenge. I have a data set with 2 subgroups,
dates (days), and corresponding values (see example code below).
Within each subgroup: I need to aggregate (sum) the values by week -
for weeks that start on a Monday (for example, 2008-12-29 was a
Monday).
I find it difficult because I have missing dates in my data - so that
sometimes I don't even have the date for some Mondays. So, I can't
write a proper loop.
I want my output to look something like this:
group   dates   value
group.1 2008-12-29  3.0937
group.1 2009-01-05  3.8833
group.1 2009-01-12  1.362
...
group.2 2008-12-29  2.250
group.2 2009-01-05  1.4057
group.2 2009-01-12  3.4411
...

Thanks a lot for your suggestions! The code is below:
Dimitri

### Creating example data set:
mydates<-rep(seq(as.Date("2008-12-29"), length = 43, by =
"day"),2)
myfactor<-c(rep("group.1",43),rep("group.2",43))
set.seed(123)
myvalues<-runif(86,0,1)
myframe<-data.frame(dates=mydates,group=myfactor,value=myvalues)
(myframe)
dim(myframe)

## Removing same rows (dates) unsystematically:
set.seed(123)
removed.group1<-sample(1:43,size=11,replace=F)
set.seed(456)
removed.group2<-sample(44:86,size=11,replace=F)
to.remove<-c(removed.group1,removed.group2);length(to.remove)
to.remove<-to.remove[order(to.remove)]
myframe<-myframe[-to.remove,]
(myframe)



-- 
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com

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PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

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Try this:

aggregate(value ~ group + format(dates, "%Y.%W"), myframe, FUN = sum)


On Wed, Mar 30, 2011 at 11:23 AM, Dimitri Liakhovitski
<dimitri.liakhovitski at gmail.com> wrote:
> Dear everybody,
>
> I have the following challenge. I have a data set with 2 subgroups,
> dates (days), and corresponding values (see example code below).
> Within each subgroup: I need to aggregate (sum) the values by week -
> for weeks that start on a Monday (for example, 2008-12-29 was a
> Monday).
> I find it difficult because I have missing dates in my data - so that
> sometimes I don't even have the date for some Mondays. So, I can't
> write a proper loop.
> I want my output to look something like this:
> group ? dates ? value
> group.1 2008-12-29 ?3.0937
> group.1 2009-01-05 ?3.8833
> group.1 2009-01-12 ?1.362
> ...
> group.2 2008-12-29 ?2.250
> group.2 2009-01-05 ?1.4057
> group.2 2009-01-12 ?3.4411
> ...
>
> Thanks a lot for your suggestions! The code is below:
> Dimitri
>
> ### Creating example data set:
> mydates<-rep(seq(as.Date("2008-12-29"), length = 43, by =
"day"),2)
> myfactor<-c(rep("group.1",43),rep("group.2",43))
> set.seed(123)
> myvalues<-runif(86,0,1)
> myframe<-data.frame(dates=mydates,group=myfactor,value=myvalues)
> (myframe)
> dim(myframe)
>
> ## Removing same rows (dates) unsystematically:
> set.seed(123)
> removed.group1<-sample(1:43,size=11,replace=F)
> set.seed(456)
> removed.group2<-sample(44:86,size=11,replace=F)
> to.remove<-c(removed.group1,removed.group2);length(to.remove)
> to.remove<-to.remove[order(to.remove)]
> myframe<-myframe[-to.remove,]
> (myframe)
>
>
>
> --
> Dimitri Liakhovitski
> Ninah Consulting
> www.ninah.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.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O