R how to simply repeat a command

Question

I m trying to repeat this simple command 10 000 times  via a simple and easy solution    Tandem  lt - sample OUT  size   815  replace   TRUE  prob   NULL   mean Tandem    Any advice would be greatly appreciated

User · Answer

You could use replicate or sapply   R gt  colMeans replicate 10000  sample 100  size 815  replace TRUE  prob NULL    R gt  sapply seq len 10000   function      mean sample 100  size 815  replace TRUE  prob NULL      replicate is a wrapper for the common use of sapply for repeated evaluation of an expression  which will usually involve random number generation

User · Answer

It s not clear whether you re asking this because you are new to programming  but if that s the case then you should probably read this article on loops and indeed read some basic materials on programming   If you already know about control structures and you want the R-specific implementation details then there are dozens of tutorials around  such as this one  The other answer uses replicate and colMeans  which is idiomatic when writing in R and probably blazing fast as well  which is important if you want 10 000 iterations    However  one more general and  for beginners  straightforward way to approach problems of this sort would be to use a for loop    gt  for  ii in 1 5      print ii       1  1  1  2  1  3  1  4  1  5  gt    So in your case  if you just wanted to print the mean of your Tandem object 5 times   for  ii in 1 5        Tandem  lt - sample OUT  size   815  replace   TRUE  prob   NULL      TandemMean  lt - mean Tandem      print TandemMean      As mentioned above  replicate is a more natural way to deal with this specific problem using R  Either way  if you want to store the results - which is surely the case - you ll need to start thinking about data structures like vectors and lists  Once you store something you ll need to be able to access it to use it in future  so a little knowledge is vital   set seed 1234  OUT  lt - runif 100000  1  2  tandem  lt - list   for  ii in 1 10000        tandem  ii    lt - mean sample OUT  size   815  replace   TRUE  prob   NULL      tandem 1  tandem 100  tandem 20 25       creates this output    gt  set seed 1234   gt  OUT  lt - runif 100000  1  2   gt  tandem  lt - list    gt  for  ii in 1 10000          tandem  ii    lt - mean sample OUT  size   815  replace   TRUE  prob   NULL        gt    gt  tandem 1    1    1  1 511923   gt  tandem 100    1    1  1 496777   gt  tandem 20 25    1    1  1 500669    2    1  1 487552    3    1  1 503409    4    1  1 501362    5    1  1 499728    6    1  1 492798   gt

[r] R : how to simply repeat a command?

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