Add rescope example

[PProfizi]

Solves #960

[codecov]

Codecov Report

Merging #961 (0a58a9a) into master (5ee39a2) will increase coverage by 0.05%.
The diff coverage is n/a.

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+ Coverage   87.24%   87.30%   +0.05%     
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  Files          81       81              
  Lines        9223     9223              
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+ Hits         8047     8052       +5     
+ Misses       1176     1171       -5     

[rafacanton]

@PProfizi From reading the example, it could be inferred that the mesh scopings are always ordered, which is not true. I mean, let's say that a user wants to have the data ordered by node Id. This example should address that. The solution offered in the example is to use the mesh scoping, but it can be the case that the mesh scoping is not ordered.

I would remark that the ascending order of the mesh scopings is not mandatory. If a user wants a 100% ordered field, then the approach that works 100% of the times is:

reordered_fields = dpf.operators.scoping.rescope_fc(
    fields_container=fields,
    mesh_scoping= np.sort(fields[0].scoping.ids),
).outputs.fields_container()

With this approach we also make sure that we don't need to tackle the default_value pin of the rescope operator, as you are rescoping with exactly the same Ids you started with (not more, not less)