Create a vector of combinations based on a table column n ames

dat <- read.table("clipboard", header=TRUE)[,-(1:3)]
dat

apply(dat > 0, 1, function(idx) paste(names(dat)[idx], collapse=" "))

From: 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