[R] runs of heads when flipping a coin
jim holtman
jholtman at gmail.com
Thu Oct 9 19:26:57 CEST 2008
You can use 'sample' and 'rle':
> x <- sample(c("H","T"), 500, replace=TRUE, prob=c(.95, .05))
> as.data.frame(unclass(rle(x)))
lengths values
1 12 H
2 1 T
3 10 H
4 1 T
5 5 H
6 2 T
7 26 H
8 1 T
9 17 H
10 1 T
11 54 H
12 1 T
13 23 H
14 1 T
15 7 H
16 1 T
17 2 H
On Thu, Oct 9, 2008 at 1:16 PM, Harvey <modelers at gmail.com> wrote:
> Can someone recommend a method to answer the following type of question:
>
> Suppose I have a coin with a probability hhh of coming up heads (and 1-hhh
> of coming up tails)
> I plan on flipping the coin nnn times (for example, nnn = 500)
> What is the expected probability or frequency of a run of rrr heads* during
> the nnn=500 coin flips?
> Moreover, I would probably (excuse the pun) want the answer for a range of
> rrr values, for example rrr = 0:50
>
> Of course I am more interested in an analytical solution than a monte carlo
> simulation solution.
>
> Thanks in advance,
>
> Harvey
>
> * OR "a run of rrr heads or more ..."
>
> [[alternative HTML version deleted]]
>
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> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
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