Here is another solution if you want to count a sequence like 00000 as three overlapping runs of 3 zeros.
> x <- sample(c(rep(0,20), rep(1,37)), 1000000, TRUE) # vector of 1M > z <- rle(x) # get the runs > indx <- which(z$values == 0 & z$lengths > 2) # find the runs > # now determine the number of 3 zeros > # if you have 00000 then this is 3 runs of three > sum(z$lengths[indx] - 2) [1] 43353 > On Mon, Jun 27, 2011 at 5:53 PM, Alexander Engelhardt <a...@chaotic-neutral.de> wrote: > Here's a one-liner. Let's see their software do that! > > sum(replicate(100, sum(sample(c(rep(0, 20), seq(1:37)), 3, replace = FALSE)) > == 0)) > > > > Am 27.06.2011 23:08, schrieb robcinm: >> >> I am taking a basic statistics course this summer, and while the majority >> of >> the class is using a statistical package that came with the book, I am >> doing >> everything in R for practical reasons. Forgive me if there is >> documentation/instruction easily available on this topic, but Google and >> forums searches left me with nothing. >> >> We are learning about randomness at the moment and are required to create >> simulations to use as an example. For the problem in the text, there are >> 57 >> numbers with 1 through 20 belonging to the same “group”, meaning the >> probability that a number in that group is picked is 20/57, and 21 through >> 57 are individuals, belonging to no larger group. The point of the >> exercise >> is to simulate the probability of 1 through 20 being chosen at random >> (with >> no replacement) three times in a row through hundreds of trials. This is >> the >> basic syntax I have been using… >> >> sample(c(rep(0, 20), seq(1:37)), 3, replace = F) >> >> That works just fine, but I am wondering if there is a more efficient way >> of >> doing this. Right now, I am hitting the up arrow and hitting “enter” >> hundreds of times and making note of each time a trial results in 0,0,0. >> If >> I place this syntax in a rep function, it just repeats the same output of >> a >> single sample x times instead of giving me new data. >> >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Simple-simulations-tp3628863p3628863.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. > > ______________________________________________ > 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. > -- Jim Holtman Data Munger Guru What is the problem that you are trying to solve? ______________________________________________ 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.
