Provides the possibility of using functions in the package through an interactive graphical user interface (GUI). Depending on input, different GUIs are opened.
When x is missing, a GUI is opened to facilitate all the steps required to create sdmData, specify the settings for the different steps, and fit sdm models.
Specifying x would be useful to interact with sdm* object. For example, if x is a sdmModels (that is generated by sdm function), a user can interactively explore the results (e.g., to see different plots of model evaluation results).