Btukfyl

I am writing a funcion whose input is a vector and output is a character vector of three levels: Below Avg, Avg, and Above Avg. I would like the character vector to be calucalted based on the 1st and 3rd quantiles of the vector given. When I call my function, only Below Avg returns which I understand why it returns, but do not know how to fix. Ideally I would like a new vector such that Below Avg corresponds to the values below the 1st quantile, Above Avg corresponds to values above the 3rd quantile, and Avg is everything in between.

x<-c(1:10)

label_scale<-function(vecrr){

  lq<-quantile(vecrr,0.25)

  uq<-quantile(vecrr,0.75)

  if(vecrr<=lq){

    k<-'Below Avg.'

  } else if(vecrr>=uq){

    k<-'Above Avg.'

  } else{

    k<-'Avg.'}

  return(k)

}

y<-mapply(label_scale,x)

z<-sapply(x,label_scale)

Your problem is that you apply your function to each one of the elements of your vector and by default a given value is always equal to the quantile of that value and your process will return Below Avg for each one of the vector elements. (Eg. x == quantile(x, 0.25) will always return TRUE).

You should use ifelse inside your function, which is vectorised:

# example vector

x<-c(1:10)



# function

label_scale<-function(vecrr){

  lq<-quantile(vecrr,0.25)

  uq<-quantile(vecrr,0.75)



ifelse(vecrr<=lq, 'Below Avg.', ifelse(vecrr>=uq, 'Above Avg.', 'Avg.'))  



}



# use function on a vector

label_scale(x)



# [1] "Below Avg." "Below Avg." "Below Avg." "Avg."       "Avg."       "Avg."       "Avg."       "Above Avg."

# [9] "Above Avg." "Above Avg."

I would use cut and quantile in this situation:

x <- c(1:10)



x.char <- cut(x, quantile(x, c(0,.25,.75,1)), include.lowest = T, labels = c('Below Avg.', 'Avg.','Above Avg.'))



x.char

[1] Below Avg. Below Avg. Below Avg. Avg. Avg. Avg. Avg.      

[8] Above Avg. Above Avg. Above Avg.

Levels: Below Avg. Avg. Above Avg.