Hi, So I have a set of data, hourly temperature, where each temperature is set up like this: Time Temp 1.04 8 1.08 10 etc. Where "1" corresponds to a day (say monday is "1", tuesday is "2") and the decimal value corresponds to an the hour of the day. I have several thousand of these readings over several months. What I would like to do is extract daily minimum temperatures from this data set. Is this possible to do with R? I'm pretty new to the use of R and have only a basic understanding of how it all works. I appreciate any help. -joe -- View this message in context: http://r.789695.n4.nabble.com/Data-Parameter-extract-tp2996369p2996369.html Sent from the R help mailing list archive at Nabble.com.
On Oct 14, 2010, at 8:56 PM, joeman3285 wrote:> > Hi, > So I have a set of data, hourly temperature, where each temperature > is set > up like this: > > Time Temp > 1.04 8 > 1.08 10 > > etc. Where "1" corresponds to a day (say monday is "1", tuesday is > "2") and > the decimal value corresponds to an the hour of the day. > > I have several thousand of these readings over several months. What > I would > like to do is extract daily minimum temperatures from this data set.> Is this possible to do with R? > > I'm pretty new to the use of R and have only a basic understanding > of how it > all works.One way that works best is for questions to include data in an R object. If those values are in a data.frame, dfrm, (and if they're not, then you need to work through some examples in the Introduction to R and the Import/Export Manual) then: dput(head(dfrm, 20)) # would get a version of the data that anyone could paste into their console. Still assuming you have this in a data.frame, perhaps: mintemps <- with( dfrm, tapply( Temp, floor(Time) , min) ) mintemps> > I appreciate any help. > > -joe > -- > View this message in context: http://r.789695.n4.nabble.com/Data-Parameter-extract-tp2996369p2996369.html > Sent from the R help mailing list archive at Nabble.com.######> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^> and provide commented, minimal, self-contained, reproducible code.-- David Winsemius, MD West Hartford, CT
Hi Joe,
Just to follow up David's advice a bit (and it is excellent
advice...there was an instance where a poster only got a response
because he or she used dput()). One sticky point for you might be how
to apply a function that finds the minimum to each day individually.
David showed you a nice way to do this, but you might be stuck because
Time includes hours (which you don't want). Here is an option to
strip off the hours, convert time to a factor (one level for each
day), and find the min (a la David).
# Your data
x <- data.frame(Time = c(1.04, 1.08), Temp = c(8, 10))
# the second argument is the factored results of
# stripping everything after the period off your Time data
tapply(x[,"Temp"], factor(gsub("\\..*", '',
x[,"Time"])), min)
Cheers,
Josh
Side rant, our system of measuring time (like the English system) is
incredibly inconvenient and illogical.
On Thu, Oct 14, 2010 at 5:56 PM, joeman3285 <joemaron at hotmail.com>
wrote:>
> Hi,
> So I have a set of data, hourly temperature, where each temperature is set
> up like this:
>
> Time ? ? Temp
> 1.04 ? ? ? ?8
> 1.08 ? ? ? ?10
>
> etc. ?Where "1" corresponds to a day (say monday is
"1", tuesday is "2") and
> the decimal value corresponds to an the hour of the day.
>
> I have several thousand of these readings over several months. ?What I
would
> like to do is extract daily minimum temperatures from this data set. ?Is
> this possible to do with R?
>
> I'm pretty new to the use of R and have only a basic understanding of
how it
> all works.
>
> I appreciate any help.
>
> -joe
> --
> View this message in context:
http://r.789695.n4.nabble.com/Data-Parameter-extract-tp2996369p2996369.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.
>
--
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/