[R] how to compare two dataset with same sampling

[William Dunlap]

merge() can align the values in the obs columns
so those with the same date can be compared.  E.g.,
set up the data with the following copy-and-pastable
code:

A <- read.table(header=TRUE, textConnection(" year  mon  day  obs
 2010 03     12    12
 2010 03     18    22
 2010 04     12    62
 2010 07      24   29
"))
B <- read.table(header=TRUE, textConnection("year  mon  day  obs
 2010 03     12    15
 2010 04     12    57
 2010 07     24    32
 2010 08     23    15
"))
AB <- merge(A, B, by=c("year", "mon", "day"), suffixes=c("A","B"))

and you can use AB to do comparisons:

> AB
  year mon day obsA obsB
1 2010   3  12   12   15
2 2010   4  12   62   57
3 2010   7  24   29   32
> with(AB, obsA - obsB)
[1] -3  5 -3

Look at help("merge") for more options.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Jie TANG
> Sent: Wednesday, August 24, 2011 6:57 PM
> To: Jeff Newmiller; r-help at r-project.org
> Subject: Re: [R] how to compare two dataset with same sampling
> 
> thanks.
>  Merge? I am just looking for a method to comparison on homogeneous sample
> between two dataset.
> 
> 
> 2011/8/25 Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
> 
> > ?merge may be what you are looking for. If not, you should clarify what you
> > want to do.
> > ---------------------------------------------------------------------------
> > Jeff Newmiller The ..... ..... Go Live...
> > DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
> > Live: OO#.. Dead: OO#.. Playing
> > Research Engineer (Solar/Batteries O.O#. #.O#. with
> > /Software/Embedded Controllers) .OO#. .OO#. rocks...1k
> > ---------------------------------------------------------------------------
> >
> > Sent from my phone. Please excuse my brevity.
> >
> > Jie TANG <totangjie at gmail.com> wrote:
> >
> >> hi ,
> >> Now I have two dataset and want to compare them with same sample.
> >> Dataset A:
> >>  year  mon  day  obs
> >>  2010 03     12    12
> >>  2010 03     18    22
> >>  2010 04     12    62
> >>  2010 07      24   29
> >>
> >> Dataset B:
> >>  year  mon  day  obs
> >>  2010 03     12    15
> >>  2010 04     12    57
> >>  2010 07     24    32
> >>  2010 08     23    15
> >>
> >>
> >> As you see,dataset A and B have several observation data but their obs data
> >> is not same everyday.
> >> Now I want to compare the data from two dataset in the same time.
> >> How could I write the R script?
> >>
> >> errdata<-subset(A,A$V11==Bdata$V11 & A$V12==B$V12)
> >>
> >> this command seems failed.How could I?
> >>
> >> --
> >>
> >> 	[[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.
> >>
> >>
> 
> 
> --
> TANG Jie
> Email: totangjie at gmail.com
> 
> 	[[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.