[R] why is this a factor?

[Ista Zahn]

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 <smartpink111 at 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 <ebs15242 at gmail.com>
> To: r-help at 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?
>
> ______________________________________________
> R-help at 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 at 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.