Or go all the way and put
options(stringsAsFactors = FALSE)
at the top your script or in your .Rprofile. This will prevent this
kind of annoyance in the future without having to say stringsAsFactors
= FALSE all the time.
Best,
Ista
On Wed, Aug 28, 2013 at 5:19 PM, arun <smartpink...@yahoo.com> wrote:
> Hi,
> Try:
> iris1<-data.frame(iris,annot=c(""),stringsAsFactors=FALSE)
> str(iris1)
> #'data.frame': 150 obs. of 6 variables:
> # $ Sepal.Length: num 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
> # $ Sepal.Width : num 3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
> # $ Petal.Length: num 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
> # $ Petal.Width : num 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
> # $ Species : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1
> 1 1 1 ...
> # $ annot : chr "" "" "" "" ...
> iris1[1,"annot"]<-"annotation"
> head(iris1,3)
> # Sepal.Length Sepal.Width Petal.Length Petal.Width Species annot
> #1 5.1 3.5 1.4 0.2 setosa annotation
> #2 4.9 3.0 1.4 0.2 setosa
> #3 4.7 3.2 1.3 0.2 setosa
>
> A.K.
>
> ----- Original Message -----
> From: Ed Siefker <ebs15...@gmail.com>
> To: r-help@r-project.org
> Cc:
> Sent: Wednesday, August 28, 2013 4:56 PM
> Subject: [R] why is this a factor?
>
> I have a table, and I want a new column to add some annotations to.
> But it ends up as a factor instead of characters, and won't let me add
> arbitrary text.
>
>> data(iris)
>> iris<-data.frame(iris,annot=c(""))
>> iris[1,"annot"]<-"annotation"
> Warning message:
> In `[<-.factor`(`*tmp*`, iseq, value = "annotation") :
> invalid factor level, NAs generated
>> class(iris[,"annot"])
> [1] "factor"
>> class(c(""))
> [1] "character"
>
> Why is c("") a character, but when I add it to a data frame it's a factor?
> What am I missing? Is there a better way to add a new column to
> a data frame?
>
> ______________________________________________
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>
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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