[R] help on replacing values

[darteta001 at ikasle.ehu.es]

Thanks a lot Gabor, that was very helpful. All sorted now!

Best

David

> Your columns are factors, not character strings.  Use as.is = TRUE as
> an argument to read.table.   Also its a bit dangerous to use T 
although
> not wrong.  Its safer to use TRUE.
> 
> On 9/7/07, darteta001 at ikasle.ehu.es <darteta001 at ikasle.ehu.es> wrote:
> > Dear List,
> >
> > I have a newbie question. I have read in a data.frame as follows:
> >
> > > data = read.table("table.txt", header = T)
> > > data
> >  X1 X2 X3 X4
> > A AB AC AB AC
> > B AB AC AA AB
> > C AA AB AA AB
> > D AA AB AB AC
> > E AB AA AA AB
> > F AB AA AB AC
> > B AB AC AB AA
> >
> > I would like to replace AA values by BB in column X2. I have tried
> > using replace() with no success, although I am not sure this is the
> > right function. This is the code I have used:
> >
> > data$X2 <- replace(data$X2, data$X2 =="AA","BB")
> > Warning message:
> > invalid factor level, NAs generated in: `[<-.factor`(`*tmp*`, list,
> > value = "BB")
> >
> > What is wrong with the code? How can I get this done? how about
> > changing AA values by BB in all 4 columns simultaneously? Actually
> > this is a small example dataframe, the real one would have about 
1000
> > columns.
> >
> > Extendind this, I found a similar thread dated July 2006 that used
> > replace() on iris dataset, but I have tried reproducing it 
obtaining
> > same warning message
> >
> >  iris$Species <- replace(iris$Species, iris$Species
> > == "setosa","NewName")
> > Warning message:
> > invalid factor level, NAs generated in: `[<-.factor`(`*tmp*`, list,
> > value = "NewName")
> >
> > Thanks in advance your help,
> >
> > David
> >
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guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>