R help - Nov 2008 - Faster way to combine data sets with different date ranges

I am trying to combine two data sets, one with daily values and one with weekly
values.  SurveyData conatins environmental data collected on a daily basis. 
sat.data contains satellite sea surface temperature that is an average of
satellite measurements over a six day period.  I would like to combine the two
files so that my output file has the daily dates from SurveyData and the weekly
average from sat.data that corresponds to that day.  I have written a loop that
does exactly what I want, but it takes a very long time.  Is there a faster way
to do this?  What I have so far is below.
Thanks,
Tim

#Compare dates
 for(i in 1:length(SurveyData$Date))
 {
 print(i)
 for(j in 1:length(sat.data$Date.Start))
  {
  if(
  sat.data$Date.Start[j]<=SurveyData$Date[i] &
  sat.data$Date.End[j]>=SurveyData$Date[i])
  survey.data[i]<- sat.data$data[j]
  }
 } 
 
#Create data frame with final data
 final.data<-data.frame(SurveyData$Record,SurveyData$Date,survey.data)
 
#Write data to file
 write.csv(final.data,file="Combined.csv")



      
	[[alternative HTML version deleted]]

See ?merge.  Also ?merge.zoo in the zoo package and sqldf
in the sqldf package (http://sqldf.googlecode.com).

Please read the last line to every message to r-help.

On Fri, Nov 7, 2008 at 6:19 PM, t c <mudiver1200 at yahoo.com>
wrote:
> I am trying to combine two data sets, one with daily values and one with
weekly values.  SurveyData conatins environmental data collected on a daily
basis.  sat.data contains satellite sea surface temperature that is an average
of satellite measurements over a six day period.  I would like to combine the
two files so that my output file has the daily dates from SurveyData and the
weekly average from sat.data that corresponds to that day.  I have written a
loop that does exactly what I want, but it takes a very long time.  Is there a
faster way to do this?  What I have so far is below.
> Thanks,
> Tim
>
> #Compare dates
>  for(i in 1:length(SurveyData$Date))
>  {
>  print(i)
>  for(j in 1:length(sat.data$Date.Start))
>   {
>   if(
>   sat.data$Date.Start[j]<=SurveyData$Date[i] &
>   sat.data$Date.End[j]>=SurveyData$Date[i])
>   survey.data[i]<- sat.data$data[j]
>   }
>  }
>
> #Create data frame with final data
>  final.data<-data.frame(SurveyData$Record,SurveyData$Date,survey.data)
>
> #Write data to file
>  write.csv(final.data,file="Combined.csv")
>
>
>
>
>        [[alternative HTML version deleted]]
>
>
> ______________________________________________
> 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.
>
>

Just expand the weekly data set to have an entry for each day and cbind
SurveyData with the new Modified.sat.data.

I was having a similar problem but with dates and here was a solution suggested
by Gustaf Rydevik using rep() with the each option.
=======================================================================time<-rep(1:24,
365)
dates<-seq(as.Date("01012005",format="%d%m%Y"),as.Date("31122005",format="%d%m%Y"),by=1)
TimeFrame<-data.frame(time)
TimeFrame$dates<-rep(dates,each=24)
========================================================================



--- On Fri, 11/7/08, t c <mudiver1200 at yahoo.com> wrote:
> From: t c <mudiver1200 at yahoo.com>
> Subject: [R] Faster way to combine data sets with different date ranges
> To: r-help at r-project.org
> Received: Friday, November 7, 2008, 6:19 PM
> I am trying to combine two data sets, one with daily values
> and one with weekly values.? SurveyData conatins
> environmental data collected on a daily basis.? sat.data
> contains satellite sea surface temperature that is an
> average of satellite measurements over a six day period.? I
> would like to combine the two files so that my output file
> has the daily dates from SurveyData and the weekly average
> from sat.data that corresponds to that day.? I have written
> a loop that does exactly what I want, but it takes a very
> long time.? Is there a faster way to do this?? What I have
> so far is below.
> Thanks,
> Tim
> 
> #Compare dates
> ?for(i in 1:length(SurveyData$Date))
> ?{
> ?print(i)
> ?for(j in 1:length(sat.data$Date.Start))
> ??{
> ??if(
> ??sat.data$Date.Start[j]<=SurveyData$Date[i] &
> ??sat.data$Date.End[j]>=SurveyData$Date[i])
> ??survey.data[i]<- sat.data$data[j]
> ??}
> ?} 
> ?
> #Create data frame with final data
> ?final.data<-data.frame(SurveyData$Record,SurveyData$Date,survey.data)
> ?
> #Write data to file
> ?write.csv(final.data,file="Combined.csv")
> 
> 
> 
>       
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.

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