Hi I presume your data frames are not big. What about merging them by hour and comparing appropriate columns?
something like windMerged<-merge(windHW, spring, by = "hour", all=TRUE) sel <- which(windMerged[, xx] >= windMerged[,yy]) windMerged[sel, xx] <- NA Untested because lack of data. Cheers Petr > -----Original Message----- > From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of > Alexandra Catena > Sent: Friday, April 10, 2015 11:07 PM > To: r-help@r-project.org > Subject: Re: [R] Finding values in a dataframe at a specified hour > > Update: > > I have this so far. * The first column of windHW is the wind speed. > The 5th column of the dataframe, spring, is the 5*sigma value of every > hour. hourRow gives out all the rows of wind speed at a given hour. > > for (i in 0:23){ > hourRow = which(windHW$hour==i,arr.ind=TRUE) > for (h in hourRow){ > if (windHW[h,1]>=spring[spring$hour==i,5]){ > windHW[h,1]<-NA} > } > } > > This then gives the error: Error in if (windHW[h, 1] >= > spring[spring$hour == i, 5]) { : argument is of length zero > > *Note: The dataframe for each of the seasons have 24 rows corresponding > to each hour of the day 0:23. > > Thanks, > Alexandra > > > On Fri, Apr 10, 2015 at 1:07 PM, Alexandra Catena <amc5...@gmail.com> > wrote: > > Hello, > > > > I have a large dataframe (windHW) of wind speeds (ws) at each hour > > from many days over a set of years. Some of these values are > > obviously wrong (600 m/s) and I want to get rid of all the values > that > > are larger than 5*sigma for each hour. The 5*sigma (variable name > > sigma5) values are located in different dataframes for each season, > > with each dataframe titled as a season. For example, in the > > dataframe, spring, the 5*sigma value is 79.6 m/s for hour 1. > > > > So my question is as follows: how can I get it so that the code will > > be able to find all the wind speed values in the dataframe, windHW, > of > > a specific hour be higher than the 5*sigma value at that hour? > > For example, I would like to find if any of the wind speed values at > > hour 1 are higher than 79.6 m/s, and if so, then replace that value > > with NA. > > > > I have something like this but I can't seem to figure out how to get > > it for specific hours: > > > > windHW$ws[windHW$ws>=spring$sigma5] <- NA > > > > I imported the data using readLines and into the dataframe windHW. I > > also have R version 3.1.1 > > > > Any help would be appreciated! > > > > Thanks, > > Alexandra > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. ________________________________ Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a jsou určeny pouze jeho adresátům. Jestliže jste obdržel(a) tento e-mail omylem, informujte laskavě neprodleně jeho odesílatele. Obsah tohoto emailu i s přílohami a jeho kopie vymažte ze svého systému. Nejste-li zamýšleným adresátem tohoto emailu, nejste oprávněni tento email jakkoliv užívat, rozšiřovat, kopírovat či zveřejňovat. Odesílatel e-mailu neodpovídá za eventuální škodu způsobenou modifikacemi či zpožděním přenosu e-mailu. 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