Added categorical data example

[Joao-Dionisio]

No description provided.

[Jiunixo]

Hello,
Thank you for your work and all these nice and pedagogic examples.
Trying this specific one, I think that the following constraints are missing :

• each employee must be assigned to exactly one shift

# Each employee must be assigned to exactly one shift
for e in employees:
    model.addCons(sum(x[e, s] for s in shift_to_int.values()) == 1)

So, if you test the original example with cost = {
"Alice": [2,4,1],
"Bob": [3,3,2],
"Charlie": [3,3,3]
},
then Bob is assigned to 2 shifts and Charlie to none.
I can create issue and PR if it helps.

[Joao-Dionisio]

Oops, you're exactly right @Jiunixo, thank you for pointing it out! If you wouldn't mind creating a PR, I can merge it straight away :)

[Jiunixo]

It's done there #939
I'm not very used to GitHub, don't hesitate to tell me if something goes wrong : )