Hi If you want to remove rows with NA values from your data you could use
?complete.cases or t2 <- t1[!is.na(t1$Petal.Width),] Cheers Petr > -----Original Message----- > From: R-help <r-help-boun...@r-project.org> On Behalf Of Rui Barradas > Sent: Saturday, January 12, 2019 12:55 PM > To: Ernest Han <ernest....@gmail.com>; r-help@r-project.org > Subject: Re: [R] NA rows appeared in data.frame > > Hello, > > You have to test for NA. Some (12) of the values of t1$Petal.Width are NA > therefore t1$Petal.Width == 2.0 alone returns 12 NA values. > > t1[t1$Petal.Width == 2.0 & !is.na(t1$Petal.Width == 2.0), ] > > Or use which(t1$Petal.Width == 2.0). > > t1[which(t1$Petal.Width == 2.0), ] > > > Hope this helps, > > Rui Barradas > > Às 08:23 de 12/01/2019, Ernest Han escreveu: > > Dear All, > > > > After replacing some values in a data.frame, NAs rows have appeared > > and cannot be removed. I have googled these issues and found that > > several people have encountered it. Solutions in stackoverflow seem to > > provide work-arounds but does not remove it from the data.frame. > > Therefore, I am turning to experts in this community for help. > > > > The code is as follows, > > > >> t1 <- iris > >> t1[t1$Petal.Width==1.8, "Petal.Width"] <- NA t1[t1$Petal.Width == > >> 2.0, ] > > Sepal.Length Sepal.Width Petal.Length Petal.Width Species > > NA NA NA NA NA <NA> > > NA.1 NA NA NA NA <NA> > > NA.2 NA NA NA NA <NA> > > NA.3 NA NA NA NA <NA> > > 111 6.5 3.2 5.1 2 virginica > > 114 5.7 2.5 5.0 2 virginica > > NA.4 NA NA NA NA <NA> > > 122 5.6 2.8 4.9 2 virginica > > 123 7.7 2.8 6.7 2 virginica > > NA.5 NA NA NA NA <NA> > > NA.6 NA NA NA NA <NA> > > NA.7 NA NA NA NA <NA> > > NA.8 NA NA NA NA <NA> > > 132 7.9 3.8 6.4 2 virginica > > NA.9 NA NA NA NA <NA> > > NA.10 NA NA NA NA <NA> > > 148 6.5 3.0 5.2 2 virginica > > NA.11 NA NA NA NA <NA> > > > > ## Twelve values were replaced, twelve NA rows appeared. > > > > ### MISC INFO ### > >> sessionInfo() > > R version 3.4.0 (2017-04-21) > > Platform: x86_64-apple-darwin16.5.0 (64-bit) Running under: macOS > > 10.14.2 > > > > Matrix products: default > > BLAS: > > /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/ > > vecLib.framework/Versions/A/libBLAS.dylib > > LAPACK: > > /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/ > > vecLib.framework/Versions/A/libLAPACK.dylib > > > > locale: > > [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8 > > > > attached base packages: > > [1] stats graphics grDevices utils datasets methods base > > > > loaded via a namespace (and not attached): > > [1] compiler_3.4.0 tools_3.4.0 > >> Sys.getlocale() > > [1] "en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8" > > > > > > Thank you, > > Ernest > > > > ______________________________________________ > > 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. > > > > ______________________________________________ > 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. Osobní údaje: Informace o zpracování a ochraně osobních údajů obchodních partnerů PRECHEZA a.s. jsou zveřejněny na: https://www.precheza.cz/zasady-ochrany-osobnich-udaju/ | Information about processing and protection of business partner’s personal data are available on website: https://www.precheza.cz/en/personal-data-protection-principles/ Důvěrnost: Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a podléhají tomuto právně závaznému prohláąení o vyloučení odpovědnosti: https://www.precheza.cz/01-dovetek/ | This email and any documents attached to it may be confidential and are subject to the legally binding disclaimer: https://www.precheza.cz/en/01-disclaimer/ ______________________________________________ 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.