Bizzarre error in compound statement in R?: "target of assignment expands to non-language object"

Question

I have a very strange thing happening in R. This code gives the following error, "Error in 1 && CurrentData$phase[i] > -0.5 || PriorData$phase[MatchTimeFrames(i, : target of assignment expands to non-language object"

  return (CurrentData$phase[i-1]<-1 && CurrentData$phase[i]>-0.5 || 
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)-1]<-1 &&
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] > -0.5 ||  
         CurrentData$phase[i]>0 ||
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] >0
       )

If I comment out the first condition, the code runs.

  return (#CurrentData$phase[i-1]<-1 && CurrentData$phase[i]>-0.5 || 
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)-1]<-1 &&
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] > -0.5 ||  
         CurrentData$phase[i]>0 ||
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] >0
       )

If I comment out the second condition, the code runs.

  return (CurrentData$phase[i-1]<-1 && CurrentData$phase[i]>-0.5 || 
         #PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)-1]<-1 &&
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] > -0.5 ||  
         CurrentData$phase[i]>0 ||
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] >0
       )

Obviously, I want both conditions to run and what made it work was putting a space between the less than sign and the -1 on the second condition.

 return (CurrentData$phase[i-1]<-1 && CurrentData$phase[i]>-0.5 || 
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)-1]< -1 && PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] > -0.5 ||  
         CurrentData$phase[i]>0 ||
         PriorData$phase[MatchTimeFrames(i, CurrentData, PriorData)] >0
       )

Any idea why that is happening? It seems very strange that in this particular instance R is requiring a space between the less than sign and -1. Notice that the first term, CurrentData$phase[i-1]<-1, has no space.

Thank you.

`<-` is assignment. You must put a space between the `<` and `-`. — Matthew Lundberg, Dec 27 '13 at 02:00

score 4 · Answer 1 · answered Dec 27 '13 at 02:04

4

It's because <- is assignment. Here is a shorter example, which makes it more clear what is happening:

> x <- 1 && y <- 2
Error in 1 && y <- 2 : 
  target of assignment expands to non-language object

answered Dec 27 '13 at 02:04

Matthew Lundberg

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Painfully obvious now. Thank you Matthew for pointing this out. – mks212 Dec 27 '13 at 02:13

Bizzarre error in compound statement in R?: "target of assignment expands to non-language object"

1 Answers1