These mapfiles are created for PICRUSt2's add_description script to group MetaCyc pathways into few categories.
add_descriptions.py -i pathways_out/path_abun_unstrat.tsv
--custom_map_tabl ../metacyc_pathways_info_prokaryotes_top_level.tsv
-o pathways_out/path_abun_unstrat_descrip.tsv
The top level of MetaCyc pathway looks like this, while the second level is the child classes of the top classes.
Though this level may not be analogous to KEGG's BRITE hierarchy, it gives me a quick insight of the predicted pathways.
Please note that some pathways belong to more than one class. For example, pathway PWY-7013 belongs to both Degradation/Utilization/Assimilation and Generation of Precursor Metabolite and Energy classes. However, I was not aware of this by the time I create the mapfiles. So always check the MetaCyc website if you have any question.
Also note that I accessed the MetaCyc website to create these mapfiles at Dec. 2, 2018, so the pathway description is subject to change.