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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 ?

Improve this question
5
  • works for me. you might also want to use v <- Vectorize(categorize_cov) instead, then you can use v(...) like a function without mapply Commented Dec 15, 2024 at 5:24
  • 1
    value is an entire column. The R if function cannot handle entire columns. Commented Dec 15, 2024 at 5:36
  • @IRTFM But I do the same thing by explicitly stating the column and the code works. It only is failing when I use indices to reference the column Commented Dec 17, 2024 at 14:51
  • Without a minimal reproducible example we are not going to see this Q as worthy of further effort. We don’t know the structural aspects of your data. The error indicates the ‘if’ function has been given a longer object than it can handle. Commented Dec 17, 2024 at 16:17
  • OK I will make up a dataset Commented Dec 17, 2024 at 16:35
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