Checking the auto.arima
function, I noticed it internally calls another function which is named arima.string
.
Then I did:
getAnywhere(arima.string)
and the output was:
A single object matching ‘arima.string’ was found
It was found in the following places
namespace:forecast
with value
function (object)
{
order <- object$arma[c(1, 6, 2, 3, 7, 4, 5)]
result <- paste("ARIMA(", order[1], ",", order[2], ",", order[3],
")", sep = "")
if (order[7] > 1 & sum(order[4:6]) > 0)
result <- paste(result, "(", order[4], ",", order[5],
",", order[6], ")[", order[7], "]", sep = "")
if (is.element("constant", names(object$coef)) | is.element("intercept",
names(object$coef)))
result <- paste(result, "with non-zero mean")
else if (is.element("drift", names(object$coef)))
result <- paste(result, "with drift ")
else if (order[2] == 0 & order[5] == 0)
result <- paste(result, "with zero mean ")
else result <- paste(result, " ")
return(result)
}
Then I copied the function code and pasted it in a new function which I named arima.string1
arima.string1(fm)
# [1] "ARIMA(2,1,0) with drift "