Groupby for regular array

[tk3369]

Never mind. There is already a good post.

Allocation - groupby

I’m attempting to create a function groupby(f, itr) that returns a dictionary whose keys are the results of applying f to the elements of itr, and the values are some collection of the elements themselves. Similar to Mathematica’s GroupBy. Example, groupby(iseven, 1:5) --> Dict(true=>(2, 4), false =>(1, 3, 5)). The type of the values doesn’t need to be a tuple if there’s a better alternative. This is partly because I need it, and partly because I’m learning Julia. So, both answers that explain …