How to specify groups order?

[makarov-ccf]

Hello,

Any plot I make where I need to compare samples by group, the groups are always listed alphabetically. Is it a way to position them in specified order? Example is attached. I wanted to plot in order: Pre, Post, but unless I added xPost, the order was always Post, Pre (i.e. alphabetically)

Thank you

repertoire_diversity_status.pdf