Add clearer example of adding objects to a group in tutorial

[donno]

From the tutorial / user guide of geoh5py it is not obvious or clear how to place an object in a group.

I initially tried group.add_children(grid) however that didn't work. After a little bit of digging through the code I discovered the create() function (really this is Workspace.create_entity()) takes a parent parameter which is the group to add the entity to.

The drillhole example does show this but I had overlooked it as I wasn't interested in drillholes.

It would also be good to cover how to move an object between groups if that is possible through Python.

[domfournier]

Hi Sean @donno ,

Thank you for this. The add_children method should be working. Our unit test for it is quite simple (maybe too simple):

geoh5py/tests/point_data_test.py

Line 91 in abdd3bd

def test_add_children(tmp_path):

I think the issue could be that you did close the workspace after the command. The project tree gets re-written on close only.
If that is not the issue, could you provide a code snippet to replicate what you see?

Best,

Dom

[donno]

I should have reported the version I was using. 0.9.2. It looks like a day after my post you released 0.10.

The snippet that replicated it was:

    with Workspace.create(arguments.output) as workspace:
        group = ContainerGroup.create(workspace, name="My Group")
    
        grid = Grid2D.create(workspace, u_count=10, v_count=8,
                             u_cell_size=0.15, v_cell_size=0.15,
                             origin=(50, 50, 0.0),
                             name="Example")
        group.add_children(grid)
        if  grid.parent != group:
             raise ValueError("Error adding children to group.")

The ValueError is raised and removing the if/raise the file saves and then view it in Geoscience ANALYST , the grid is in the root of the workspace rather than in the group.

I upgraded to 0.10.0 (wheel or source for it has not yet been not been uploaded to PyPI at this time).
Adding the object the group via add_children() works in this version. 👍

However, there is issue with the new version, it expects `h5repack" to be available on the path and due to the use of shell that outputs an error on Windows). I can raise a fresh issue for that.

As for the tutorial, perhaps it could be something like extending the current example to have:

# Add a group to a group.
sub_group = ContainerGroup.create(workspace, name="subGroup")
group.add_children(sub_group)

[donno]

After digging deeper into the h5repack issue, raised in #693. I realised that the disadvantage to using add_children() rather than Type.create(.., parent=group) is that the item is initially parented to the root at creation anyway and then moved which triggers a repack on close.