[R] controlling the number of times a script is repeated in a loop

[Salas, Andria Kay]

I am running a large for loop and at the end of each iteration a matrix is produced.  The program changes the columns in the matrix, and each time a column is added the name of that column is "y".  All original columns have no column name.  Due to the nature of the program, all original columns will eventually be replaced with new columns each with the column name "y". It is at this point that I want the program to stop running the for loop (right now I just have it running for 20 iterations resulting in a matrix with a mix of old and new columns).  I was thinking maybe I could do something with an if else statement and the command colnames.  For example:

If(colnames all are "y") (stop) else (run the program again)

Not entirely sure how to go about this though, or if I am even on the right track.  Maybe I need to get rid of the master for loop as perhaps for loops are more constraining in the number of times the program is run?  The number of runs to get all original columns replaced with new ones will never be the same (I plan on running this several times, with time steps ending when all original columns are replaced.  Perhaps at the end of each time step I can set column names to have no column names (so from "y"s to nothing), allowing me to use this method for each time step)...

I know it is always helpful to have some code to work with, but it seems impractical to send the whole program as one part if it I am still working on and would probably just create more confusion.  Hopefully someone might be able to offer a few suggestions...I can try to come up with a toy program to send along but I am not good enough in R yet to do this quickly!

Thank you for all the help and I am sorry if this question is perhaps a bit confusing!  If I have not made my problem and what I hope to do clear, please let me know.