The issue I believe is how CurrentDay is entered. It was previously created as:
Transaction <- function(PnL, Day)
results <- list(a = PnL, b = Day)
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.