f is a dataframe of factor, not a factor
use either
as.numeric(levels(f$your.factor))[f$your.factor]
or if f only contains factors
apply(f, 2, function(x){as.numeric(levels(x))[x]})
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium
+ 32 2 525 02 51
+ 32 54 43 61 85
thierry.onkel...@inbo.be
www.inbo.be
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asking him to perform a post-mortem examination: he may be able to say what the
experiment died of.
~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data.
~ Roger Brinner
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-----Oorspronkelijk bericht-----
Van: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] Namens
John Coulthard
Verzonden: vrijdag 13 april 2012 15:08
Aan: r-help@r-project.org
Onderwerp: [R] How do I convert factors to numeric? It's an FAQ but...
Dear R list people
I loaded a file of numbers into R and got a dataframe of factors. So I tried
to convert it to numeric as per the FAQ using as.numeric(). But I'm getting
errors (please see example), so what am I getting wrong?
Thanks for your time.
John
Example...
#my data object
> f
GSM187153 GSM187154 GSM187155 GSM187156 GSM187157 GSM187158 GSM187159
13 7.199346 7.394519 7.466155 8.035864 7.438536 7.308401 7.707994
14 6.910426 6.360291 6.228221 7.42918 7.120322 6.108129 7.201477
15 8.85921 9.152096 9.125067 6.4458 8.600319 8.97577 9.691167
16 5.851665 5.621529 5.673689 6.331274 6.160159 5.65945 5.595156
17 9.905257 8.596643 9.11741 9.872789 8.909299 9.104171 9.158998
18 6.176691 6.429807 6.418132 6.849236 6.162308 6.432743 6.444664
19 7.599871 8.795133 8.382509 5.887119 7.941895 7.666692 8.170374
20 9.458262 8.39701 8.402015 9.0859 8.995632 8.427601 8.265105
21 8.179803 9.868286 10.570601 4.905013 9.488779 9.148336 9.654022
22 7.456822 8.037138 7.953766 6.666418 7.674927 7.995109 7.635158
GSM187160 GSM187161 GSM187162
13 7.269558 7.537711 7.099806
14 6.61534 7.125821 6.413295
15 8.64715 8.252031 9.445682
16 5.639816 5.9257 5.752994
17 8.856829 9.043991 8.839183
18 6.4307 6.71052 6.5269
19 7.674577 7.390617 8.638025
20 8.132649 8.755642 8.137992
21 9.897561 7.619129 10.242096
22 7.836658 7.297986 8.679438
> class(f)
[1] "data.frame"
#all the columns in the dataframe are of class 'factor'
> for(i in 1:ncol(f)){if(class(f[,i])!="factor"){print(class(f[,i]))}}
>
#but it won't convert to numeric
> g<-as.numeric(as.character(f))
Warning message:
NAs introduced by coercion
> g
[1] NA NA NA NA NA NA NA NA NA NA
> g<-as.numeric(levels(f))[as.integer(f)]
Error: (list) object cannot be coerced to type 'integer'
>
R version 2.14.1 (2011-12-22)
Copyright (C) 2011 The R Foundation for Statistical Computing ISBN 3-900051-07-0
Platform: i386-redhat-linux-gnu (32-bit)
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