问对tsibble进行预处理以运行fable包中的时间序列模型

EN

# Packages
library(tidyverse)
library(tsibble)
library(fable)
library(fabletools)

# Simulated data
id <- c(rep (222, 28), rep(111, 36), rep(555, 16))
year <- c(rep(2014, 12), rep(2015, 12), rep(2016, 4), 
          rep(2014, 12), rep(2015, 12), rep(2016, 12), 
          rep(2015, 12), rep(2016, 4))
mnt <- c(seq(1, 12, by = 1), seq(1, 12, by = 1), seq(1, 4, by = 1),
         seq(1, 12, by = 1), seq(1, 12, by = 1), seq(1, 12, by = 1),
         seq(1, 12, by = 1), seq(1, 4, by = 1))
value <- rnorm(80, mean = 123, sd = 50)
dataf <- data.frame(id, mnt, year, value)

dataf$mnt[dataf$mnt == 1] <- "Jan"
dataf$mnt[dataf$mnt == 2] <- "Feb"
dataf$mnt[dataf$mnt == 3] <- "Mar"
dataf$mnt[dataf$mnt == 4] <- "Apr"
dataf$mnt[dataf$mnt == 5] <- "May"
dataf$mnt[dataf$mnt == 6] <- "Jun"
dataf$mnt[dataf$mnt == 7] <- "Jul"
dataf$mnt[dataf$mnt == 8] <- "Aug"
dataf$mnt[dataf$mnt == 9] <- "Sep"
dataf$mnt[dataf$mnt == 10] <- "Oct"
dataf$mnt[dataf$mnt == 11] <- "Nov"
dataf$mnt[dataf$mnt == 12] <- "Dec"

dataf %>% unite("time", mnt:year, sep = " ")

tsbl <- as_tsibble(dataf, index = time, key = id)

> tsbl <- as_tsibble(dataf, index = time, key = id)
Error: `var` must evaluate to a single number or a column name, not a function
Call `rlang::last_error()` to see a backtrace.

# Fitting arima 
fit <- tsbl %>%
  fill_gaps(b = 0) %>% 
  model(
    arima = ARIMA(value),
  )
fit

# One month ahead forecast
fc <- fit %>%
  forecast(h = 1)
fc

# Accuracy measure
accuracy_table <- accuracy(fit)