in R, how to capture ARIMA elements from auto.arima results - r

Question

I have a bunch of series to forecast using forecast::auto.arima function. I like to save what type of model did auto.arima fit. If you run the following code:
library(forecast)
set.seed(123)
y <- sin(seq(-pi,pi,0.05))+(rnorm(length(seq(-pi,pi,0.05)))/4)
arima.model <- auto.arima(y)
arima.model
the result of the last line execution shows
Series: y
**ARIMA(1,1,2)**
Coefficients:
ar1 ma1 ma2
0.9594 -1.7285 0.7740
s.e. 0.0380 0.0745 0.0658
sigma^2 estimated as 0.06534: log likelihood=-6.1
AIC=20.2 AICc=20.53 BIC=31.51
How can I capture ARIMA(1,1,2) and save results? I was hoping to do something like arima.model$ and capture what I need to but I could not figure it out.

Answer 1

You can try summary(arima.model), arima.model$coef, arima.model$aic, arima.model$bic.
If you want a tidy format, you can use broom package like this:
library(broom)
tidy(arima.model) #ar/ma terms
glance(arima.model) #information criteria
tidy(arima.model)
# A tibble: 3 x 3
term estimate std.error
<fct> <dbl> <dbl>
1 ar1 0.959 0.0380
2 ma1 -1.73 0.0745
3 ma2 0.774 0.0658
glance(arima.model)
# A tibble: 1 x 4
sigma logLik AIC BIC
<dbl> <dbl> <dbl> <dbl>
1 0.256 -6.10 20.2 31.5