I am trying to be more elegant in my coding and leveraging the apply functions. I wanted to stick one in a loop like so

for (ind in (ind2fix ))
{
  ADPPK[,ind] = mapply(categorize_cov,value = ADPPK[,ind-4], low = ADPPK[,ind-2],high = ADPPK[,ind-1],doserec = ADPPK$EVID)  
}

with the function defined as

categorize_cov <- function(value, low, high, doserec)
{  
  if (doserec == 0)
  {
    if (value > high)
      return("HIGH")
    else if (value < low )
      return("LOW")
    else
      return("NORMAL")
  }
  else
  {
    return(NA)
  }
}

I get the following error

Error in if (value > high) return("HIGH") else if (value < low) return("LOW") else return("NORMAL") : 
  the condition has length > 1

what is confusing is if I write it out rather than use indexing to specify the column it works as expected?

explicitly specifying the columns works but I have to do this like 20 times which is annoying

mapply(categorize_cov,value = ADPPK$GLU, low = ADPPK$GLUL,high = ADPPK$GLUH,doserec = ADPPK$EVID)  

Is there a way I can loop it ?