[R] See the numeric codes of a factor

Angel Rodriguez angel.rodriguez at matiainstituto.net
Fri Sep 19 14:12:01 CEST 2014

Thank you, Duncan. So isn't it possible to add labels to a variable with numeric values 0/1? This kind of variable is very useful for logistic regression, for example, but I'd rather have its categories labelled.


De: Duncan Murdoch [mailto:murdoch.duncan at gmail.com]
Enviado el: vie 19/09/2014 13:32
Para: Angel Rodriguez; r-help at r-project.org
Asunto: Re: [R] See the numeric codes of a factor

On 19/09/2014, 6:53 AM, Angel Rodriguez wrote:
> Dear Subscribers,
> I want to label a numeric variable 0="Bad" /1="Good". I understand the only way is to transform it into a factor variable.
> Is there a way to check that the numeric values of the new factor variable are 0 and 1 and not 1 and 2?

If you apply as.numeric() to a factor, you won't get a zero value.
Internal factor values start at 1.

So I wouldn't rely on the internal storage to achieve whatever it is you
want to achieve.  Use explicit computation, e.g.

words <- ifelse(var == 0, "Bad", ifelse(var == 1, "Good", NA))
values <- ifelse(words == "Bad", 0, ifelse(words == "Good", 1, NA))

Duncan Murdoch

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