How to set node set Ids

[adityaghantasala]

Hello I am working on converting some of my input into exodus format.
Seacas has been very helpful. Thank you for the work.

Now i am stuck with defining node sets. I have some node sets in my own format. To set these into exodus format, I am using the following code

node_set_ids = range(1,10)
set_nodes = [5,9]
status = my_exo.put_node_set(1, set_nodes)

But unfortunately, it results in a an error saying no set with id 1 is found. I tried to set the node set ids but cannot find a suitable function to do.

Can you point me to the necessary setps to do this ?

Thank you in advance.

[gsjaardema]

When you first define the exodus model, you will tell it how many node sets the model will contain (num_ns):

        >>> status = exo.put_info(title, num_dims, num_nodes, num_elems,
        ...                      num_blocks, num_ns, num_ss)

Then, for each of those num_ns nodesets, you tell exodus the ID and count of nodes and distribution factors:

        >>> exo.put_set_params('EX_NODE_SET', node_set_id,
        ...                 num_ns_nodes, num_ns_dist_facts)

You can then use your code above to actually output the set_nodes. Somewhat convulted and not really pythonic, but this is driven by the C API...

Hope that helps.

[adityaghantasala]

Hi Thank you for the quick reply.
Yes This works.
Thanks again !

[gsjaardema]

You might also be interested in using exomerge https://gsjaardema.github.io/seacas-docs/exomerge.pdf which is a higher-level interface to the exodus library and provides some higher-level convenience functions. It has a function
create_node_set --- Create a node side from the given list of node indices. which does most of this in an single step:

Example
>>> model.create_node_set(1, [0, 1, 2, 3])

[adityaghantasala]

I will have a look at this. Thanks for the hint.