Mutate Element of Range View

Asked Mar 01 '19 at 15:32

Active Mar 04 '19 at 16:00

Viewed 107 times

I have a 2-dimensional vector of enums std::vector<std::vector<enum>>, the enum can have the values a (0), b (1), c(2). I would like to randomly set one of the a's to c and thought I'll try out the ranges library.

Currently I have a view of all the as in my 2d vector using this:

auto g = view::join(vec) | filter([](my_enum x){ return x == my_enum::a; };

I found view::sample that sounds useful to randomly select an element, but didn't know how to use it since I got confused about the size of another range it needs as a parameter? (view::sample doc)

Next step would also be to mutate that randomly selected element. As far as I understood it, ranges::v3::view only provides a non-mutable view on elements. So is it at all possible to mutate a selected element?

edited Mar 04 '19 at 16:00

asked Mar 01 '19 at 15:32

DenverCoder21

I'm confused by `return x : enumname::a;`. In what context is that valid C++? Did you mean `==` instead of `:`? – Max Langhof Mar 01 '19 at 17:13
Yes, sorry that was a typo. `return x == my_enum::a` for example. – DenverCoder21 Mar 03 '19 at 17:48

Mutate Element of Range View

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