On 28/06/18 16:25, Nicolas Rolin wrote:
Hi,I use list and dict comprehension a lot, and a problem I often have is to do the equivalent of a group_by operation (to use sql terminology). For example if I have a list of tuples (student, school) and I want to have the list of students by school the only option I'm left with is to write student_by_school = defaultdict(list) for student, school in student_school_list: student_by_school[school].append(student) What I would expect would be a syntax with comprehension allowing me to write something along the lines of: student_by_school = {group_by(school): student for school, student in student_school_list} or any other syntax that allows me to regroup items from an iterable.
Sorry, I don't like the extra load on comprehensions here. You are doing something inherently somewhat complicated and then attempting to hide the magic. Worse, you are hiding it by pretending to be something else (an ordinary comprehension), which will break people's intuition about what is being produced.
-- Rhodri James *-* Kynesim Ltd _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
