On the spatial distance between training and validation data in model evaluation

The code for reproducing the experiment and result is stored in "Origin_code.rar", with the required data stored in "Data_files.rar". Specifically:

1. 'simulation_experiment.R' is for reproducing the simulation experiment.
2. 'Modelling.R' is for reproducing the case study.
3. "Casestudy_Rmarkdown.pdf" is the R markdown for showing the outputs for the case study step by step.
4. 'compute_sliding_window_metrics.R' is the function for the moving distance validation (MDV) model
5. 'fun_spatially_weighted_validation.R' is the function for spatial validation.