Hello All, Suppose that I have a sequence of letters (e.g., A..Z). I want to permute the sequence to generate random sequences, such that the local density of any letter with a window (say of length L) doesn't change much before and after permutation.
One way that I can thing of is to require that the position of any letter in the original sequence and the position of the same letter in the new sequence should be smaller than L. Suppose that v is the original sequence of letters. The following R code random generates the sequence but without the distance constraint as mentioned above. sample(v, length(v)) To generate a random sequence, an intuitive idea is to break the sequence into chunks of length L, then permute freely within each chunk. The chunks are then slided 1 letter each time (until L-1 times) and more sequence are generated. My method may be crude. I'm wondering if there is a well established method to generate a sequence satisfying the same local distribution. -- Tom ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
