Grid ID

[kbarnhart]

@mdpiper and @mcflugen another question motivated by making the terrainbento bmi:

I see that there are a number of functions in the bmi.py file that indicate needing a grid identifier. The best/most relevant part of the documentation that I can find was this section on Variables[sic?] Grids. It does not give me enough information.

Reading between the lines I think that what this is saying is that I'm allowed to define multiple grids within my model. If I do this, I need to give them unique IDs that are integers and allow them to be accessed in this way. Correct?

[mcflugen]

Correct. A BMI implementation may have multiple grids and each grid must have a unique identifier (as an integer).

Note that variables may be defined on different grid elements of a single grid. For example, you are allowed to have variables defined on a grid's nodes and edges. In such a case, your component would still have a single grid.

Another note: BMI and landlab use a different nomenclature for grid elements.

landlab	BMI
node	node
link	edge
patch	face
corner	node
face	edge
cell	face

BMI doesn't have the concept of a dual grid like landlab does so the dual grid elements of landlab are a separate grid with their own nodes, edges, and faces.

[kbarnhart]

@mcflugen very helpful -- thank you! Closing.

[mcflugen]

@kbarnhart Ooops. I just noticed I made a mistake in the above. landlab patches are BMI faces (not patches). I've updated the comment to reflect the correct names.