R help - Nov 2010 - how to save this result in a vector

HI, Dear R community,

I have the following codes to calculate the commulative coverage. I want to
save the output in a vector, How to do this?

test<-seq(10, 342, by=2)

#cover is a vector
cover_per<-function (cover) {
for (i in min(cover):max(cover)) {print(100*sum(ifelse(cover >= i, 1,
0))/length(cover))}
}

result<-cover_per(test)
> result
NULL

Can anyone help me this this?




-- 
Sincerely,
Changbin
--

	[[alternative HTML version deleted]]

Hi Changbin,

The yek is that you need to save the results of your for loop rather
than just printing it.  It also may be possible to vectorize your for
loop which might simplify things and speed them up, but I did not look
at that.  Here is one way to save the results, see inline comments for
more details.

Cheers,

Josh


##############################

test<-seq(10, 342, by=2)

#cover is a vector
cover_per <- function(cover) {
  ## create a vector to store the results of your for loop
  output <- vector("numeric", length(min(cover):max(cover)))
  for (i in min(cover):max(cover)) {
    ## rather than print()ing the output, assign it to an object
    output[i] <- 100*sum(ifelse(cover >= i, 1, 0))/length(cover)
  }
  ## have the return value from the function be
  ## the object 'output'
  return(output)
}

## here the results will be printed to the screen
## (the results are just the 'output' object)
cover_per(test)
## if you assign it to another object, nothing is printed
## but you can easily print 'result' if you want
result <- cover_per(test)

##############################


On Sun, Oct 31, 2010 at 5:35 PM, Changbin Du <changbind at gmail.com>
wrote:
> HI, Dear R community,
>
> I have the following codes to calculate the commulative coverage. I want to
> save the output in a vector, How to do this?
>
> test<-seq(10, 342, by=2)
>
> #cover is a vector
> cover_per<-function (cover) {
> for (i in min(cover):max(cover)) {print(100*sum(ifelse(cover >= i, 1,
> 0))/length(cover))}
> }
>
> result<-cover_per(test)
>
>> result
> NULL
>
> Can anyone help me this this?
>
>
>
>
> --
> Sincerely,
> Changbin
> --
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> 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
http://www.joshuawiley.com/

On Oct 31, 2010, at 8:35 PM, Changbin Du wrote:
> HI, Dear R community,
>
> I have the following codes to calculate the commulative coverage.
Not sure exactly what you mean by this. My guess is implemented below.
> I want to
> save the output in a vector, How to do this?
>
> test<-seq(10, 342, by=2)
>
> #cover is a vector
> cover_per<-function (cover) {
> for (i in min(cover):max(cover))
Using either for (i in cover) { ...} or for (i in seq_along(cover) )  
{...} would be more typical.
> {print(100*sum(ifelse(cover >= i, 1,
> 0))/length(cover))}
> }
>
> result<-cover_per(test)
Are you looking for cumsum?

 > test<-seq(10, 34, by=2)
 > 100*cumsum(test)/sum(test)
  [1]   3.496503   7.692308  12.587413  18.181818  24.475524   
31.468531  39.160839
  [8]  47.552448  56.643357  66.433566  76.923077  88.111888 100.000000

 > print(100*cumsum(test)/sum(test), digits=2)
  [1]   3.5   7.7  12.6  18.2  24.5  31.5  39.2  47.6  56.6  66.4   
76.9  88.1 100.0

-- 

David Winsemius, MD
West Hartford, CT