Source:

In the following example dataset, students took the same test three times, and their scores were stored in any array in the Scores column.

Transformation:

When the data is imported, you might have to re-type the Scores column as an array:

You can now unnest the Scores column data into separate columns:

In the above transformation:

• Each path is specified in a separate row. 
  • The [x] syntax indicates that the path is the xth element of the array. 
  • The first element of an array is referenced using [0]. 
• You can choose to delete the element from the original or not. Deleting the element can be a helpful way of debugging your transformation. If all of the elements are gone, then the transformation is complete. 
• If you include the original column name in the output column names, you have some contextual information for the outputs.

Results: