[R] Need some help

[azzza]

Umm, yes, what you had makes a lot of sense. How would I represent that in a
plot of the number of sign changes in the to  Y axis, and the toss number
(from 0 to 1000) in the x-axis? 




jholtman wrote:
> 
> You might want to check out 'rle'.  This will give you the 'lengths'
> of runs of the same value and therefore when the value changes (sign
> change?) you can see how often:
> 
>> x <- sample(c(-1,1), 1000, TRUE)
>> rle(x)
> Run Length Encoding
>   lengths: int [1:483] 2 2 1 4 3 1 1 1 1 2 ...
>   values : num [1:483] -1 1 -1 1 -1 1 -1 1 -1 1 ...
> 
> Here was a sample of 1000, and there were 483 changes between the
> samples.  Is this what you are looking for?
> 
> On 10/15/07, azzza <azza.khogaliali at utoronto.ca> wrote:
>>
>>
>> Quite helpful indeed. Greatly appreciated.
>> Another problem I had was trying to simulate an example from my book.
>> Simulating 1000 coin tosses, and finding the frequency of sign changes.
>> So
>> how will we plot this using R? (frequency of sign changes in Y axis)
>>
>>
>>
>>
>> Daniel Nordlund wrote:
>> >
>> >> -----Original Message-----
>> >> From: r-help-bounces at r-project.org
>> [mailto:r-help-bounces at r-project.org]
>> >> On Behalf
>> >> Of azzza
>> >> Sent: Sunday, October 14, 2007 10:21 PM
>> >> To: r-help at r-project.org
>> >> Subject: [R] Need some help
>> >>
>> >>
>> >> Hi!
>> >> I'm taking a course that requires some programming background, but I'm
>> a
>> >> complete novice in the field.
>> >>
>> >> when asked to generate a list of 20 uniform random numbers, is it
>> alright
>> >> if
>> >> I put in >randu, and just copy-paste the first 20 numbers?? Or is
>> there,
>> >> as
>> >> I suspect, a better way of calling out exactly 20 uniform random
>> >> numbers??
>> >>
>> > See ?runif
>> >
>> > rand_nums <- runif(20)
>> >
>> >> I'm also unable to solve the following problem:
>> >> We know that on average 30% of the customers who enter a store make a
>> >> purchase. Suppose 200
>> >> people enter the store today. Run a simulation to see how many
>> purchases
>> >> we
>> >> will have today.
>> >>
>> > see ?sample
>> >> number_of_purchases <- sum(sample(c(0,1), 200, prob=c(.70, .30),
>> >> replace=TRUE))
>> >
>> > Hope this is helpful,
>> >
>> > Dan
>> >
>> > Daniel Nordlund
>> > Bothell, WA USA
>> >
>> > ______________________________________________
>> > R-help at 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.
>> >
>> >
>>
>> --
>> View this message in context:
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>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
>> R-help at 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
> Cincinnati, OH
> +1 513 646 9390
> 
> What is the problem you are trying to solve?
> 
> ______________________________________________
> R-help at 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.
> 
> 

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