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The issue I believe is how CurrentDay is entered. It was previously created as:

Transaction <- function(PnL, Day) results <- list(a = PnL, b = Day) return(results)

Both PnL and Day are numeric values.

Day <- Transaction(PnL, Day)["b"]

Where Transaction returned a list and b is an integer.

moving_avg <- function(StockData, MA, CurrentDay){ #MA = Days long the MA is #CurrentDay = What day we are currently on MAValue <- NULL total <- 0 start <- CurrentDay - MA for(i in 1:length(MA)) { total <- total + StockData[[start, 4]] start <- start + 1 } MAValue <- total/MA return(MAValue) }

Anyone know why I am receiving this error?

Error in CurrentDay - MA : non-numeric argument to binary operator

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    Please include sample data and show exactly how you are calling the function. See how to make a reproducible example. Commented Apr 16, 2015 at 4:42
  • 1
    The function's ok, you probably called it with non-numeric argument. Please provide a reproducible sample, like @MrFlick said. Commented Apr 16, 2015 at 4:44
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    I think I found the issue, CurrentDay is being imputed from a variable I designated from a list. When I just print CurrentDay I get $b [1] 41 Commented Apr 16, 2015 at 4:53

2 Answers 2

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88

Because your question is phrased regarding your error message and not whatever your function is trying to accomplish, I will address the error.

- is the 'binary operator' your error is referencing, and either CurrentDay or MA (or both) are non-numeric.

A binary operation is a calculation that takes two values (operands) and produces another value (see wikipedia for more). + is one such operator: "1 + 1" takes two operands (1 and 1) and produces another value (2). Note that the produced value isn't necessarily different from the operands (e.g., 1 + 0 = 1).

R only knows how to apply + (and other binary operators, such as -) to numeric arguments:

> 1 + 1 [1] 2 > 1 + 'one' Error in 1 + "one" : non-numeric argument to binary operator

When you see that error message, it means that you are (or the function you're calling is) trying to perform a binary operation with something that isn't a number.

EDIT:

Your error lies in the use of [ instead of [[. Because Day is a list, subsetting with [ will return a list, not a numeric vector. [[, however, returns an object of the class of the item contained in the list:

> Day <- Transaction(1, 2)["b"] > class(Day) [1] "list" > Day + 1 Error in Day + 1 : non-numeric argument to binary operator > Day2 <- Transaction(1, 2)[["b"]] > class(Day2) [1] "numeric" > Day2 + 1 [1] 3

Transaction, as you've defined it, returns a list of two vectors. Above, Day is a list contain one vector. Day2, however, is simply a vector.

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5 Comments

looking at my code, is my Day variable not a numeric value based on how it is originally set at the beginning? If not, what must I do to make it one?
I have a similar problem, only I’m getting it when trying to join to plots (a boxplot and a jitterplot) that run fine separately. My error message reads ‘Error in p + o : non-numeric argument to binary operator’. Should I create a separate question for this, or is this something that should be discussed here in the comments?
@CannedMan this is largely unrelated but easy to fix. If you are trying to put them next to each other use par(mfrow = c(1,2) or par(mfrow = c(2,1). Else call the first plot and then use points() or the like
"R only knows how to apply + (and other binary operators, such as -) to numeric arguments" - tiny caveat: except in ggplot (& ggmap etc) pipes, where "+" is used like the %>% pipe.
@dez93_2000 true!
1

If you run this before your code, everything is gonna be OK.

'+' <- function(e1, e2) { if (is.character(e1) | is.character(e2)) { paste0(e1, e2) } else { base::`+`(e1, e2) } }
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