[R] need help in customising function in stat_summary function ggplot2

[William Dunlap]

Your code,
  cnt = 0
  for(i in 1:length(x)){
   ifelse(x[i] > median(x),cnt+1,cnt)
  }
sets cnt to zero and never sets it to anything else.  Hence it is zero
at the end of the loop.  if you set cnt to the value of your call to ifelse
you should get the desired result
    cnt <- ifelse(x[i] > median(x),cnt+1,cnt)

By the way, the more R-ish way of counting the number of x strictly
greater than the median is just
   cnt <- sum(x > median(x))
instead of those 4 lines above.
('cnt' should be about length(x)/2 unless there are a lot of points at the
median).

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Thu, Oct 20, 2016 at 1:25 AM, Indhira, Anusha <
Anusha.Indhira at controlsdata.com> wrote:

> Hi,
>
> I would like to print percentage of points in a group which are greater
> than median value in boxplot. I have tried below code but it always prints
> zero in the graph. Can you let me know, how to modify code to get desired
> result?
>
>
> perc.greaterthan.median <- function(x){
>   cnt = 0
>   for(i in 1:length(x)){
>    ifelse(x[i] > median(x),cnt+1,cnt)
>   }
>   return(c(y = median(x)*1.7, label = round((cnt/length(x))*100,2)))
> }
>
> ggplot(st_chg_51, aes(x=factor(st_dv), P3))+ #label=rownames(st_chg_51))) +
>   geom_boxplot(fill = "grey80", colour = "#3366FF") +
>   stat_summary(fun.data = perc.greaterthan.median, geom = "text", fun.y =
> median) +
>   theme_bw()+theme(axis.text = element_text(angle = 90, hjust = 1))
>
> Why does cnt in the function doesn't get incremented in the loop?
>
> Thanks,
> Anusha
>
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