simpleR | Using R for Introductory Statistics | Analytics library

Suppose that we have a very long array, of, say, int to make the problem simpler.

What is the fastest way (or just a fast way, if it's not the fastest), in C++ to see if an array has more than one common elements in C++?

To clarify, this function should return this:

so - I have built a bit of a rules engine in python - but I'm fairly new to python... my engine is fairly nice to use - but adding a new rule is pretty ugly, and I'm wondering if there's a way to clean it up.

The key thing to remember is that rules have side-effects, rules can be combined with ands, ors, etc - and you only apply the side effects if the whole rule succeeded - ie the check if the rule succeeded can't be combined with perfoming the side effect.

So every rule ends up looking something like this:

My question is about synchronizing threads. Basically, if I have an OpenMP code in Fortran, each thread is doing something. There are two possibilities for synchronizing them (let some variable have the same value in each thread), I think.

1. add !$OMP BARRIER
2. add !$OMP END PARALLEL. If necessary, add !$OMP PARALLEL and !$OMP END PARALLEL block later on.

Are options 1) and 2) equivalent? I saw some question about barrier in nested threads omp barrier nested threads So far I am more interseted in simpler scanarios with Fortran. E.g., for the code below, if I use barrier, it seems the two if (sum > 500) then conditions will behave the same, at least by gfortran.

I asked a question yesterday about template method overloading and resolving issues using type traits. I received some excellent answers, and they led me to a solution. And that solution led me to more reading.

I landed on a page at Fluent CPP -- https://www.fluentcpp.com/2018/05/18/make-sfinae-pretty-2-hidden-beauty-sfinae/ that was interesting, and then I listened to the Stephen Dewhurst talk that Mr. Boccara references. It was all fascinating.

I'm now trying to understand a little more. In the answers yesterday, I was given this solution:

There is a nice question (Which substitution failures are not allowed in requires clauses?) proposing the next problem.

One needs to write a compile-time function template constexpr bool allTypesUnique() that will return true if all argument types are unique, and false otherwise. And the restriction is not to compare the argument types pairwise. Unfortunately, the answer only explains why such function cannot be implemented with some particular approach.

I think the solution can be achieved using multiple inheritance. The idea is to make a class inherited from a number of classes: one for each type T in Ts. And each such class defines a virtual function with a signature depending on T. If some T is found more than once in Ts then function f in a child class will override the function in a base class and it can be detected:

edit: I have followed up with a more specific question. Thank you answerers here, and I think the followup question does a better job of explaining some confusion I introduced here.

TL;DR I'm struggling to get proofs of constraints into expressions, while using GADTs with existential constraints on the constructors. (that's a serious mouthful, sorry!)

I've distilled a problem down to the following. I have a simple GADT that represents points called X and function applications called F. The points X are constrained to be Objects.

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3255.html defines decay_copy as follows:

My goal is to create this plot in ggplot2:

After a lot of fiddling around, I managed to create it for this one dataset, as per the screenshot above, with the following rather fragile code (note the width=63, boundary=410, which took lots of trial and error):

I'm wondering if there's any simpler way to assign multiple columns in Python, just like the := in R data.table.

For example, in Python I would have to write like this: