[R] control the conversion of factor to numeric

[R. Michael Weylandt]

Use the stringsAsFactors = FALSE argument for read.table() so the
strings will remain factors and then you can convert them directly
yourself.

Michael

On Tue, Oct 18, 2011 at 9:40 AM, Martin Batholdy
<batholdy at googlemail.com> wrote:
> Ok, I think that would work – thanks!
>
> However, in my case I read a data.frame via read.table().
> So some of the columns get transformed to factors automatically –
> I don't generate the factor-variables as in the example, so I can't control how the levels are ordered (or can I?).
>
>
>
> On 18.10.2011, at 15:35, R. Michael Weylandt wrote:
>
>> Add levels= to your factor() call.
>>
>> E.g.,
>>
>> x1 <- factor(rep(1:4, 5), labels=c("slightly disagree", "disagree",
>> "agree", "slightly agree"), levels = c(2,1,4,3))
>> as.numeric(x1)
>> [1] 2 1 4 3 2 1 4 3 2 1 4 3 2 1 4 3 2 1 4 3
>>
>> Michael
>>
>> On Tue, Oct 18, 2011 at 7:35 AM, Martin Batholdy
>> <batholdy at googlemail.com> wrote:
>>> Dear R-list,
>>>
>>>
>>>
>>> I currently have to convert a data.frame with several factor-variables to a numeric matrix.
>>>
>>> Now the problem is, that the order of the factor-labels don't match the order I would like to use.
>>>
>>>
>>> for example, let's assume I have this factor-variable in my data-frame:
>>>
>>> x <- factor(rep(1:4, 5), labels=c("slightly disagree", "disagree", "agree", "slightly agree"))
>>>
>>>
>>> Now I would like to convert this to a numeric vector so that disagree == 1, slightly disagree == 2, slightly agree == 3, and agree gets the value 4.
>>> but as.numeric(x) just converts the factor levels to numerical values according to their label-order.
>>>
>>>
>>> Is there a convenient, flexible function that let's you control how the factor-levels get converted to numerical values?
>>>
>>>
>>>
>>> thanks for any suggestions!
>>>
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>
> ______________________________________________
> 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.
>