Hi Petr, many thanks for your reply and the examples.
My subscripting problems drive me nuts. I have understood that dataset[variable] is semantically identical to dataset[, variable] cause dataset[variable] takes all cases because no other subscripts are given. Where can I lookup the rules when to use the comma and when not? Kind regards Georg Von: PIKAL Petr <petr.pi...@precheza.cz> An: "g.maub...@weinwolf.de" <g.maub...@weinwolf.de>, Kopie: "r-help@r-project.org" <r-help@r-project.org> Datum: 27.06.2016 11:03 Betreff: RE: [R] Antwort: Fw: Re: Subscripting problem with is.na() Hi see in line > -----Original Message----- > From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of > g.maub...@weinwolf.de > Sent: Monday, June 27, 2016 10:45 AM > To: David L Carlson <dcarl...@tamu.edu>; Bert Gunter > <bgunter.4...@gmail.com> > Cc: r-help@r-project.org > Subject: [R] Antwort: Fw: Re: Subscripting problem with is.na() > > Hi David, > Hi Bert, > > many thanks for the valuable discussion on NA in R (please see extract > below). I follow your arguments leaving NA as they are for most of the > time. In special occasions however I want to replace the NA with another > value. To preserve the newly acquired knowledge for me I wrote this > function: > > -- cut -- > t_replace_na <- function(dataset, variable, value) { > if(inherits(dataset[[variable]], "factor") == TRUE) { > dataset[variable] <- as.character(dataset[variable]) > print(class(dataset[variable])) > dataset[, variable][is.na(dataset[, variable])] <- value > dataset[variable] <- as.factor(dataset[variable]) > print(class(dataset[variable])) > } else { > dataset[, variable][is.na(dataset[, variable])] <- value > } > return(dataset) > } > <snip> > class(ds_test[, "c"]) > test_class(ds_test, "c") > warning("'c' should be factor NOT data.frame. > In addition data.frame != factor") > -- cut -- > > Why do I get different results for the same function if it is inside or > outside my own function definition? Because you still are missing the way how to subscript data frames. test_class <- function(dataset, variable) { if(inherits(dataset[, variable], "factor") == TRUE) { return(c(class(dataset[,variable]), TRUE)) #### ^^^^ } else { return(c(class(dataset[,variable]), FALSE)) ###### ^^^^ } } > test_class(ds_test, "a") [1] "numeric" "FALSE" > test_class(ds_test, "c") [1] "factor" "TRUE" > If you properly arrange commas in your function you get desired result p_replace_na <- function(dataset, variable, value) { if(inherits(dataset[,variable], "factor") == TRUE) { dataset[,variable] <- as.character(dataset[,variable]) print(class(dataset[,variable])) dataset[, variable][is.na(dataset[, variable])] <- value dataset[, variable] <- as.factor(dataset[, variable]) print(class(dataset[, variable])) } else { dataset[, variable][is.na(dataset[, variable])] <- value } return(dataset) } > p_replace_na(ds_test, "c", value = -3) [1] "character" [1] "factor" a b c 1 1 NA A 2 NA NA b 3 2 NA -3 > t_replace_na(ds_test, "c", value = -3) [1] "data.frame" Error in sort.list(y) : 'x' must be atomic for 'sort.list' Have you called 'sort' on a list? > Cheers Petr > > Kind regards > > Georg > > -------------------------------- > > > Gesendet: Donnerstag, 23. Juni 2016 um 21:14 Uhr > > Von: "David L Carlson" <dcarl...@tamu.edu> > > An: "Bert Gunter" <bgunter.4...@gmail.com> > > Cc: "R Help" <r-help@r-project.org> > > Betreff: Re: [R] Subscripting problem with is.na() > > > > Good point. I did not think about factors. Also your example raises > another issue since column c is logical, but gets silently converted to > numeric. This would seem to get the job done assuming the conversion is > intended for numeric columns only: > > > > > test <- data.frame(a=c(1,NA,2), b = c("A","b",NA), c= rep(NA,3)) > > > sapply(test, class) > > a b c > > "numeric" "factor" "logical" > > > num <- sapply(test, is.numeric) > > > test[, num][is.na(test[, num])] <- 0 > > > test > > a b c > > 1 1 A NA > > 2 0 b NA > > 3 2 <NA> NA > > > > David C > > ______________________________________________ > 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 jak�koliv k n�mu p�ipojen� dokumenty jsou d�v�rn� a jsou ur�eny pouze jeho adres�t�m. Jestli�e jste obdr�el(a) tento e-mail omylem, informujte laskav� neprodlen� jeho odes�latele. 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