This looks good to me! I like the tests for loading from files.

I think most people who want to load from Excel would want to load different components from different sheets within the same workbook, as you say. But it would be nice to be flexible about using different files too.

Perhaps an API like this? But definitely open to suggestions if you have a better idea.

Dataset.from_excel(flows_filename, process_filename=None, material_filename=None, 
                   time_filename=None, flows_sheet=None, process_sheet=None, 
                   material_sheet=None, time_sheet=None)

• from_excel('workbook.xlsx') would load just the flows from the first sheet
• from_excel('workbook.xlsx', flows_sheet='Flows') would load just the flows from the sheet called 'Flows'
• from_excel('workbook.xlsx', flows_sheet=2) would load just the flows from the 3rd sheet (this isn't essential but it would just work with pandas I think)
• from_excel('workbook.xlsx', flows_sheet='Flows', process_sheet='Processes') would load flows and processes from same workbook
• from_excel('workbook.xlsx', process_filename='processes.xlsx', process_sheet='Processes') would load flows from the first sheet in 'workbook.xlsx' and processes from the 'Processes' sheet of 'processes.xlsx'

For the material and time tables, you're right, we don't actually have an example of using this at the moment. It could look like this, if you want to add one.

Materials:

Time:

Also, while you're at it please could you add yourself to the list of contributors at the end of the README (assuming you're happy to be listed there)?

Hi @neiljp, just wondering if you are still planning to do any more on this? No hurry if so, just let me know at some point.