Hi, sklearn Pipelines are awesome, I use them all the time for everything. I've been writing a lot custom transformers lately, and since most of my transformers require no fitting (e.g. replacing all number with "{NUM}" token), I started using transformers as decorators. See snippet (example usage at the end): https://github.com/urigoren/decorators4DS/blob/master/decorators4DS/sklearn_... Do you think this kind of addition should be a part of sklearn ? -- *Uri Goren,* *Phone: +972-507-649-650* *EMail: uri@goren4u.com <uri@goren4u.com>* *Linkedin: il.linkedin.com/in/ugoren/ <http://il.linkedin.com/in/ugoren/>*