examples: Rename model.grid to model.space

[rht]

Fixes #1227.

[rht]

Ugh, this is actually a breaking change, because HexGridVisualization and CanvasGridVisualization assume model.grid. Should we introduce this breaking change?

[tpike3]

Ugh, this is actually a breaking change, because HexGridVisualization and CanvasGridVisualization assume model.grid. Should we introduce this breaking change?

This is a pretty big one where I think the majority of user visualizations will break. I started working through some work arounds but none were suitable, so will think more on it.

Broad strokes I think there is three paths:

• we do it
• we don't do it
• we keep grid for the examples in HexGridVisualization and CanvasGridVisualization as they are grids and change the others which are not grid

[rht]

There is always room for adding an informative error message, at the right time. In the 2 classes, we check if users have model.grid defined. If so, we raise an exception telling what is wrong, and recommend people to use model.space.

[Corvince]

I think this is not worth a breaking change. I think we should either

1. Do what @rht said, but with a warning or
2. Allow both .grid and .space, but think about how to deal with this in the future.

The reason for 2 is that I think depending on an implicit naming scheme is bad practice. We should either somehow enforce a name or leave the choice completely open to the users.

[tpike3]

I think this is not worth a breaking change. I think we should either

1. Do what @rht said, but with a warning or
2. Allow both .grid and .space, but think about how to deal with this in the future.

The reason for 2 is that I think depending on an implicit naming scheme is bad practice. We should either somehow enforce a name or leave the choice completely open to the users.

Concur, and I vote 2 as we have already had issues with implicit naming and my bias would be to leaving the choice to the users

[rht]

We sidestepped the model.datacollector naming by introducing model.initialize_datacollector (which does initial data collection under the hood, where people often forget to do). But we can't do the same with space/grid, because with datacollector, >90% of the case it is mesa.DataCollector, but with space, it could be SingleGrid, MultiGrid, NetworkGrid, ...

[Corvince]

We could just add space as an additional function parameter to the modules. CanvasGrid currently takes model width and space, but doesn't actually use them, don't know how that evolved. But I think this is a clean solution and should even he doable without breakage.

[rht]

The width and height could be passed explicitly, but what about

mesa/mesa/visualization/modules/CanvasGridVisualization.py

Line 97 in 685494d

cell_objects = model.grid.get_cell_list_contents([(x, y)])

?

[Corvince]

The width and height could be passed explicitly, but what about

mesa/mesa/visualization/modules/CanvasGridVisualization.py

Line 97 in 685494d

cell_objects = model.grid.get_cell_list_contents([(x, y)])

?
(
Sorry I realised my comment was a bit confusing. I would just add a space parameter (with a space instance) and derive everything needed from that. The width/height is just an oddity i saw when analysing CancasGrid.
Just to be clear, a complete example might look something like this

mycanvas = CanvasGrid(grid=mymodel.space, canvas_width=500,  canvas_height=500)

[Corvince]

Since the examples are now in their own repo this can be closed