[R] Looping with looping

[ani jaya]

Thank you very much, Dr. Snow, your suggestion helps a lot.

Best,
Saat

On Fri, Apr 19, 2019 at 4:14 AM Greg Snow <538280 using gmail.com> wrote:

> When the goal of looping is to compute something and save each
> iteration into a vector or list, then it is usually easier to use the
> lapply/sapply/replicate functions and save the result into a single
> list rather than a bunch of global variables.
>
> Here is a quick example that does the same computations as your code,
> but save the results into a list where each element is a vector of
> length 100:
>
> sam<-c(9,7,8,6,6,7,8,6,7,3)
> a <- lapply(2:9, function(k){
>   replicate(100, mean(sample(sam, k, replace=TRUE)))
> })
>
> # optional
> names(a) <- sprintf("a%i", 2:9)
>
> hist(a[["a2"]]
> hist(a$a9)
> w <- "a5"
> hist(a[[w]])
>
>
> Saving everything into a single list (or matrix/array/etc.) makes it
> easier to loop over all of the results later on (and prevents the hard
> to track down bugs from using dynamically named global variables).
> Here is an example based on the results from above:
>
> par(mfrow=c(3,3))
> for(i in seq_along(a)) {
>   hist(a[[i]], xlab='x', main=sprintf("k = %i", (2:9)[i]))
> }
>
>
>
>
>
> On Thu, Apr 18, 2019 at 9:19 AM ani jaya <gaaauul using gmail.com> wrote:
> >
> > Dear R community,
> >
> > I'm trying to create a looping to see the effect of number of samples
> from
> > one dataset.
> > Lets say I have 10 values in a single data frame and I want to see the
> mean
> > of each sampling let say from 2-9 number of sampling. But I want to do
> the
> > repetition let say up to 100 for each number of sampling and put it in a
> > different dataframe, let say a2,a3,a4,... which contain a2[1] is the mean
> > of first repetition and so on. I believe this is possible but I'm newbie
> > here.
> >
> > > version
> >
> > platform       x86_64-w64-mingw32
> > arch           x86_64
> > os             mingw32
> > system         x86_64, mingw32
> > status
> > major          3
> > minor          5.3
> > year           2019
> > month          03
> > day            11
> > svn rev        76217
> > language       R
> > version.string R version 3.5.3 (2019-03-11)
> > nickname       Great Truth
> >
> >
> >  The simple code that I have:
> >
> > sam<-c(9,7,8,6,6,7,8,6,7,3)
> > for (k in seq(2,9,1)){
> >     a <- numeric(100)
> >       for (i in 1:100){
> >       a[i] <- mean(sample(sam,k,replace=T))
> >
> >       }
> >   }
> >
> > I can do enough with this code but i want to the variable name also
> > move based on k.
> >
> > I have googling enough and meet assign and paste command but not really
> help.
> > Any help would be appreciate.
> >
> >
> >
> > Best,
> >
> > Saat M.
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
>
>
> --
> Gregory (Greg) L. Snow Ph.D.
> 538280 using gmail.com
>

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