R: forecasting multiple time series from a single data frame - r

Question

I am trying to forecast multiple time series data that are present in a single data frame.
The dataframe df looks like below. The dput(df) is given below as well to reproduce quickly.
Date Group Value
01-04-2019 Saffron 62.78
01-04-2019 Green 75.65
01-05-2019 Saffron 67.89
01-06-2019 Saffron 54.56
01-06-2019 Green 77.00
01-07-2019 Green 71.22
structure(list(Date = structure(c(1L, 1L, 2L, 3L, 3L, 4L), .Label = c("01-04-2019", "01-05-2019", "01-06-2019", "01-07-2019"), class = "factor"),
Group = structure(c(2L, 1L, 2L, 2L, 1L, 1L), .Label = c("Green",
"Saffron"), class = "factor"), Value = c(62.78, 75.65, 67.89,
54.56, 77, 71.22)), .Names = c("Date", "Group", "Value"), class = "data.frame", row.names = c(NA, -6L))
Objective: I want to forecast for each Group using forecast package.
So my approach was as follows:
col_name_date <- "Date"
col_name_measure <- "Value"
col_name_sku_depo <- "Group"
dates_to_forecast <- 3
for (v in unique(as.character(df$Group))) {
temp <-subset(data,Group == v)
assign(paste0("df_",tolower(v)),temp)
temp <- temp [order(temp[, col_name_date]), ]
start_date <- as.Date(temp[1, col_name_date], date_format) #< ---library(lubridate)
ts_historic <- ts(temp[, col_name_measure],
start = c(year(start_date), month(start_date)),
frequency = 12)
----Forecasting process using forecast package, omitting as it is out of scope-----
forecast_mean <- rep(NA, dates_to_forecast)
forecast_mean <- ts_forecast$mean
forecast_upper <- ts_forecast$upper
forecast_lower <- ts_forecast$lower
dates_all_mean <- as.numeric(c(as.numeric(ts_historic), as.numeric(forecast_mean)))
dates_all_lower <- as.numeric(c(rep(NA, length(ts_historic)), as.numeric(forecast_lower)))
dates_all_upper <- as.numeric(c(rep(NA, length(ts_historic)), as.numeric(forecast_upper)))
result <- data.frame(
MONTH = dates_all,
MEASURETYPE = date_types,
GROUP = v
MEASURE = dates_all_mean,
MEASURELOWER = dates_all_lower,
MEASUREUPPER = dates_all_upper,
MODEL = model_descr)
}
The above code works fine for a single Group i.e. Saffron. But this doesn't produce the result for Green group.
I am looking for the following output:
MONTH MEASURETYPE GROUP MEASURE MEASUREUPPER MEASURELOWER MODEL
01-04-2019 Actual Saffron 62.78 NA NA Test
01-05-2019 Actual Saffron 67.89 NA NA Test
01-06-2019 Actual Saffron 54.56 NA NA Test
01-07-2019 Forecast Saffron 55.35 56.15 54.23 Test
01-08-2019 Forecast Saffron 57.29 58.15 56.39 Test
01-04-2019 Actual Green 75.65 NA NA Test
01-05-2019 Actual Green 77.00 NA NA Test
01-06-2019 Actual Green 71.22 NA NA Test
01-07-2019 Forecast Green 76.35 77.15 75.23 Test
01-08-2019 Forecast Green 73.29 74.29 72.30 Test
As you can see from the code, I am able to generate the above output only for Saffron.
How can I also add Green as shown in the above output?
Where I am missing out in for loop?