# Cell Specimen Mapping¶

The cross-session alignment algorithm has been updated and re-run just prior to release 0.13.2 (June 15th, 2017). As a result all cell specimen IDs have changed. We have built a mapping table to help map from previous cell IDs to new cell IDs. The table is available as a WellKnownFile and the BrainObservatoryApi provides a method for downloading it and loading it as a DataFrame.

The BrainObservatoryApi provides a get_cell_specimen_id_mapping method for downloading the mapping table as a CSV file. The method requires a file name to save the table to, and will return the table as a DataFrame.
The cell specimen mapping table contains 4 columns, old_cell_id, session_A_new_cell_id, session_B_new_cell_id, session_C_new_cell_id. In some instances, multiple ROIs that were assigned to a single cell specimen may now be considered distinct cells after reprocessing, so an old cell specimen ID may map to different cell specimens in different sessions.