Given that your labels are "no" and "yes", what do you expect R to
do? To quote a well-known fortune, "R is lacking a mind_read() function!"
cheers,
Rolf Turner
On 01/23/2013 10:58 PM, Francesco Sarracino wrote:
Thanks,
this works! but I am surprised that R has such a strange behavior and that
there is no way to control it.
BTW, also as.integer(pp)-1 works!
Still, it doesn't look to me as a first best.
At any rate, thanks a lot for your help.
f.
On 23 January 2013 10:53, D. Rizopoulos <d.rizopou...@erasmusmc.nl> wrote:
check also
pp <- rep(0:1, 10)
pp <- factor(pp, levels=(0:1), labels=c("no","yes"))
unclass(pp)
unclass(pp) - 1
Best,
Dimitris
On 1/23/2013 10:48 AM, Francesco Sarracino wrote:
Dear Dimitris,
thanks for your quick reply. I've tried the solutions proposed in 7.10
How do I convert factors to numeric?
as.numeric(as.character(pp))
and
as.numeric(levels(pp))[as.integer(pp)]
However, whatever I do, I get "Warning message: NAs introduced by
coercion"
and the output is a vector of NA.
Any ideas?
f.
On 23 January 2013 10:39, D. Rizopoulos <d.rizopou...@erasmusmc.nl
<mailto:d.rizopou...@erasmusmc.nl>> wrote:
Check R FAQ 7.10: How do I convert factors to numeric?
I hope it helps.
Best,
Dimitris
On 1/23/2013 10:33 AM, Francesco Sarracino wrote:
> Dear R listers,
>
> I am trying to compute the mean of a dummy variable that is
encoded as a
> factor. However, even though the levels of my factor are 0 - 1,
when I
> compute the mean (after coercing the factor to be
> numeric), R changes 0 into 1 and 1 into yes, thus altering my
expected
> result.
>
> Please, consider the following working example:
> pp <- rep(0:1, 10)
> pp <- factor(pp, levels=(0:1), labels=c("no","yes"))
> mean(pp) #this won't work because the argument is not numeric or
logical
> mean(as.integer(pp)) # this computes the average, but not on the
range 0-1,
> but 1-2. Indeed, the result is 1.5 and not 0.5 as expected.
>
> What am I doing wrong?
> Thanks in advance for your kind support,
> f.
>
>
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478 <tel:%2B31%2F%280%2910%2F7043478>
Fax: +31/(0)10/7043014 <tel:%2B31%2F%280%2910%2F7043014>
Web: http://www.erasmusmc.nl/biostatistiek/
--
Francesco Sarracino, Ph.D.
https://sites.google.com/site/fsarracino/
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/
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