[R] unidentified option(s) in mean.model

Rui Barradas ruipbarradas at sapo.pt
Sat Feb 25 19:18:30 CET 2017


You're right, but the equal sign outside the function call wasn't my 
doing. I should have noticed that the OP had used
  spec = ugarchspec(...) and '<-' inside the function call to assign 
values to the function's arguments, but I heven't, so I just corrected 
the '<-'.

Rui Barradas

Em 25-02-2017 17:32, Jeff Newmiller escreveu:
> That was confusing.  One equals sign is used to assign values (actual arguments) to function inputs (formal arguments).
> The assignment operator `<-` is used to assign values to variables in the current working environment. Due to popular demand, the single equals sign can ALSO be used for that purpose, but only outside the calling parenthesis for a function call.
> I recognise that some people think this is a good argument for always using the single equals, but they are DIFFERENT operations in R, and pretending they are the same by using the same symbol in both situations just misleads people further, so at least be clear where each operator belongs when explaining the difference:
> spec <- ugarchspec(variance.model = list(model = "sGARCH",garchOrder=c(1,1)),
>                      mean.model = list(
>                        armaOrder = c(final.order[1], final.order[3]),
> arfima = FALSE, include.mean = TRUE),
>                      distribution.model = "sged")
> and then let people decide whether to use the less precise notation after they understand what is happening.
> I find it more confusing to parse
> f = function( x ) x^2
> x = 1
> x = x
> f( x = x )
> than
> f <- function( x ) x^2
> x <- 1
> x <- x
> f( x = x )
> (The x = x is just as useless as x <- x is outside the parameter list, but serves an important purpose when inside the parameter list.)

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