If you are looking to combine 2 ArrayDatastores vertically to essentially merge their data, one option would be to do a vertcat of readall outputs from both the ArrayDatastores a1 and a2.
A = cat(3,magic(10),magic(10),magic(10));
B = cat(3,magic(10),magic(10),magic(10));
a1= arrayDatastore(A);
a2= arrayDatastore(B);
data = vertcat(readall(a1), readall(a2))
You can also consider writing these data to files and then construct a single TabularTextDatastore or SpreadsheetDatastore from the files.
Another sustainable option would be to write a custom datastore that would essentially do a vertical concatenation of the datastores, instead of the horizontal concatenation done by combine.
The datastore will have 2 properties:
- a list of the underlying datastores
- index indicating which is the current underlying datastore to read from
For this datastore,
- At the beginning, we set the index to 1 and start reading from the first ArrayDatastore a1 till it has no more data.
- When hasdata for a1 is false, increment the index by 1 to point to the second ArrayDatastore a2.
The readall for this custom datastore would do a vertcat of the readall from all underlying datastores. This is extensible for more number of ArrayDatastores as we can just pass them to the custom datastore constructor.
Please see attached a sample VertcatDatastore.
Now, construct the VertcatDatastore using the ArrayDatastores a1 and a2 and do a readall.
vds = VertcatDatastore({a1, a2});
data = readall(vds)
NOTE: As we are seeing more similar queries, we are working on enabling vertically merging multiple datastores. That would essentially provide a means to read from the underlying datastores sequentially.
