R help - Jul 2011 - How to convert matrix with frequency & variable to vector?

Hi,

I have a dataset:

  freq   x
1  30    7
3  70    8
4  100  7
5  22    6
6  250  10

How do I convert into vector form (v<- 7,7,7,8,8,8,6,6,6,6) all "x"
with the
complete frequency? Transpose only does a single row but I want the full
frequencies not just the variable transposed. 

Thanks,
Nanthinee


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On Jul 8, 2011, at 12:24 AM, nanthinee wrote:
> Hi,
>
> I have a dataset:
>
>  freq   x
> 1  30    7
> 3  70    8
> 4  100  7
> 5  22    6
> 6  250  10
perhaps (untested):

c( apply(ds,1,function(x) rep(x[2], x[1]) ) )

also perhaps (since I think rep is vectorised):

rep(ds$x, ds$freq)
>
> How do I convert into vector form (v<- 7,7,7,8,8,8,6,6,6,6) all
"x"
> with the
> complete frequency? Transpose only does a single row but I want the  
> full
> frequencies not just the variable transposed.
>
> Thanks,
> Nanthinee
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/How-to-convert-matrix-with-frequency-variable-to-vector-tp3653196p3653196.html
> 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.
David Winsemius, MD
West Hartford, CT

Hi Nanthinee,

Use ?rep it will rep()licate each x, freq times.

dat <- data.frame(freq = c(30, 70, 100, 22, 250), x = c(7, 8, 7, 6, 10))
total <- rep(dat$x, dat$freq)
> length(total)
[1] 472

Cheers,

Josh


On Thu, Jul 7, 2011 at 9:24 PM, nanthinee <nanthineej at gmail.com>
wrote:
> Hi,
>
> I have a dataset:
>
> ?freq ? x
> 1 ?30 ? ?7
> 3 ?70 ? ?8
> 4 ?100 ?7
> 5 ?22 ? ?6
> 6 ?250 ?10
>
> How do I convert into vector form (v<- 7,7,7,8,8,8,6,6,6,6) all
"x" with the
> complete frequency? Transpose only does a single row but I want the full
> frequencies not just the variable transposed.
>
> Thanks,
> Nanthinee
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/How-to-convert-matrix-with-frequency-variable-to-vector-tp3653196p3653196.html
> 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.
>


-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
https://joshuawiley.com/