[R] Create a vector of combinations based on a table column names

[Eric Lecoutre]

Hi,

Here is something that does the job (though I am sure other people will 
find smarter solutions!):


 > samp=matrix(sample(0:1,size=100,replace=TRUE ,prob=c(0.8,0.2)),ncol=10)
 > colnames(samp)<-LETTERS[1:10]
 > unlist(lapply(apply(samp,1,FUN=function(vec) 
colnames(samp)[as.logical(vec)] ),paste,collapse=" "))
  [1] "A F J"   "D I"     "B I"     "A"       "G H"     "B C E H" "E 
H"     "B C E G" "E"
[10] "B C E I"

HTH,

Eric


At 16:40 23/11/2004, Henrik Andersson wrote:
>I want to create a character vector based on the table (shortened for 
>display) below:
>Where there are ones in the matrix I want the column name to appear and 
>where there are zeros nothing, which would make the vector in this 
>shortened case:
>
>combinations <- ("A B","A C","A E H","A F G","B C D","E G H",A C D E H","A 
>C D F G")
>
>     no  value  A  B  C  D  E  F  G   H
>1    2  3.095  1  1  0  0  0  0  0   0
>2    2  1.687  1  0  1  0  0  0  0   0
>46   3  3.470  1  0  0  0  1  0  0   1
>47   3  1.563  1  0  0  0  0  1  1   0
>50   3  6.234  0  1  1  1  0  0  0   0
>148  4  3.663  0  0  1  0  1  0  1   1
>151  4  3.470  0  0  0  1  1  1  0   1
>177  5  5.411  1  0  1  1  1  0  0   1
>178  5  6.829  1  0  1  1  0  1  1   0
>
>Question is how to make this not so manually?
>
>---------------------------------------------
>Henrik Andersson
>Netherlands Institute of Ecology -
>Centre for Estuarine and Marine Ecology
>P.O. Box 140
>4400 AC Yerseke
>Phone: +31 113 577473
>h.andersson at nioo.knaw.nl
>http://www.nioo.knaw.nl/ppages/handersson
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
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Eric Lecoutre
UCL /  Institut de Statistique
Voie du Roman Pays, 20
1348 Louvain-la-Neuve
Belgium

tel: (+32)(0)10473050
lecoutre at stat.ucl.ac.be
http://www.stat.ucl.ac.be/ISpersonnel/lecoutre

If the statistics are boring, then you've got the wrong numbers. -Edward 
Tufte