HI,
Below is what i'm using without including 'category' variable.
I would want to do a time series forecast with category variable included as above sample data set mentioned.
Y <- ts(df[,2], start = c(2019,2), frequency = 330)
fit_arima <- auto.arima(Y,d=1, stepwise = FALSE, approximation = FALSE, trace = TRUE)
print(summary(fit_arima))
checkresiduals(fit_arima)
fcst <- forecast(fit_arima, h=7)
autoplot(fcst)
print(summary(fcst))