Hi you could save yourself time to read help page for factor
> -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Fridolin > Sent: Monday, August 27, 2012 12:09 PM > To: r-help@r-project.org > Subject: [R] Changing entries of column of type "factor"/Adding a new > level to a factor > > What is a smart way to change an entry inside a column of a dataframe > or matrix which is of type "factor"? data.frame is not a matrix each factor have levels attribute levels(input$M1) level 0/0 shall be the first so levels(input$M1)[1] <-"999/999" Easiest way is probably cycle through columns of your data for( i in columns) levels(input[,i])[levels(input[,i])=="0/0"]<-"999/999" Regards Petr > > Here is my script incl. input data: > > #set working directory: > > setwd("K:/R") > > > > #read in data: > > input<-read.table("Exampleinput.txt", sep="\t", header=TRUE) > > > > #check data: > > input > Ind M1 M2 M3 > 1 1 96/98 120/120 0/0 > 2 2 102/108 120/124 305/305 > 3 3 96/108 120/120 0/0 > 4 4 0/0 116/120 300/305 > 5 5 96/108 120/130 300/305 > 6 6 98/98 116/120 300/305 > 7 7 98/108 120/120 305/305 > 8 8 98/108 120/120 305/305 > 9 9 98/102 120/124 300/300 > 10 10 108/108 120/120 305/305 > > str(input) > 'data.frame': 10 obs. of 4 variables: > $ Ind: int 1 2 3 4 5 6 7 8 9 10 > $ M1 : Factor w/ 8 levels "0/0","102/108",..: 5 2 4 1 4 8 7 7 6 3 $ > M2 : Factor w/ 4 levels "116/120","120/120",..: 2 3 2 1 4 1 2 2 3 2 $ > M3 : Factor w/ 4 levels "0/0","300/300",..: 1 4 1 3 3 3 4 4 2 4 > > > > #replace 0/0 by 999/999: > > for (r in 1:10) > + for (c in 2:4) > + if (input[r,c]=="0/0") input[r,c]<-"999/999" > Warnmeldungen: > 1: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") : > invalid factor level, NAs generated > 2: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") : > invalid factor level, NAs generated > 3: In `[<-.factor`(`*tmp*`, iseq, value = "999/999") : > invalid factor level, NAs generated > > input > Ind M1 M2 M3 > 1 1 96/98 120/120 <NA> > 2 2 102/108 120/124 305/305 > 3 3 96/108 120/120 <NA> > 4 4 <NA> 116/120 300/305 > 5 5 96/108 120/130 300/305 > 6 6 98/98 116/120 300/305 > 7 7 98/108 120/120 305/305 > 8 8 98/108 120/120 305/305 > 9 9 98/102 120/124 300/300 > 10 10 108/108 120/120 305/305 > > > I want to replace all "0/0" by "999/999". My code should work for > columns of type "character" and "integer". But to make it work for a > "factor"-column I would need to add the new level of "999/999" at > first, I guess. How do I add a new level? > > > > -- > View this message in context: http://r.789695.n4.nabble.com/Changing- > entries-of-column-of-type-factor-Adding-a-new-level-to-a-factor- > tp4641402.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@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. ______________________________________________ R-help@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.
