try this:

n <- 3
data.frame(Exp = seq_len(n),
    Heads = rbinom(n, 200, 0.5))


I hope it helps.

Best,
Dimitris


On 10/13/2010 7:28 PM, Shiv wrote:

I am trying a simple toin coss simulation, of say 200 coin tosses. The idea
is to have a data frame like so:
     Experiment#    Number_Of_Heads
      1                   104
      2                    96
      3                    101

So I do:

  d<-data.frame(exp_num=c(1,2,3));  /* Just 3 experiments to begin with */
  d$head_ct<-sum(sample(0:1,200,repl=TRUE));
  d;
   exp_num    head_ct
1       1        85
2       2        85
3       3        85                             /* the same scalar value is
applied to all the rows */

So I tried using "within", and "for", and making the "sum(   " as a
function, and I end up with the same...I get the same constant value.  But
what I want of course is different "samples"....




--
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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