R 中是否有 function 允许在考虑最终目标的情况下进行预测？

Question

I am looking to have 2 forecasts, one has already been created using the ets() function and predicts the next 20 months. This forecast is based off actuals and it is likely where our team is going to finish and it's going to be under 1000 units by the end of those 20 months by about 80 units (920 is the finish).

I have a 2nd forecast I would like to implement based off the end goal of 1000 units in 20 months. The purpose of this forecast is to show it as a "get back on track" forecast to show how we could make up that 80 unit difference by the end of the 20 months in order to get to 1000 units. Some rules:

• I would like for this to not be linear, preferably as an ETS forecast to compare it to forecast 1
• I have linear goals (try to add 15 units each month)
• We are already starting behind the "end 2019 goal" so I'm looking to make up that difference (hence why we're finishing behind)

Are there any functions within R that allow forecasting with a timeframe and goal already in mind?

Edit: I have been using the forecast package for my ets model.

Answer 1

Have a look at the forecast package.

Description of the package:

"Methods and tools for displaying and analysingunivariate time series forecasts including exponential smoothingvia state space models and automatic ARIMA modelling."

Link to documentation: https://cran.r-project.org/web/packages/forecast/forecast.pdf