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Since your data is in a h5 format, i suggest simply doing a 2x2 unit-square mesh, and write the data as a list of numpy nd arrays to illustrate what you would like to do.
Please note that you need to create a mapping from the data you are reading in to the corresponding degree of freedom, as there is no guarantee that your input data is ordered in the same way as the dofs (especially if you want your code to work in parallel).
Also, you will need to use a user-expression to do this efficiently.