the data derived from https://www.kaggle.com/manjeetsingh/retaildataset
we aim to forecast the weekly sales for different departments and typse of the stores
an app was created using RShiny to engage with the user the first part of the code we are reading the files and preparing them to forecast, the second part is the user interface and third part includes the server that cointains the arima model function to help us forecast the weekly sales