[R] manipulating elements of a vector

[Eric Lecoutre]

Hi,

What about:

   dummy=function(x){
         diag(length(x))[rep(1:length(x),x),]
   }

   >  dummy(c(3,2,4))
       [,1] [,2] [,3]
  [1,]    1    0    0
  [2,]    1    0    0
  [3,]    1    0    0
  [4,]    0    1    0
  [5,]    0    1    0
  [6,]    0    0    1
  [7,]    0    0    1
  [8,]    0    0    1
  [9,]    0    0    1

HTH,

Eric

At 12:23 27/05/2004, you wrote:
>Dear R users;
>
>I would like to convert a series of vectors to matrices in the following way;
>(2,1,1) to a matrix
>1 0 0
>1 0 0
>0 1 0
>0 0 1
>
>The idea is that the column sum of the matrix should be equal to the 
>elements of the vector.
>
>Thanks.
>
>Vumani

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

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Tufte