Fastest way to put contents of Set to a single String with words separated by a whitespace?

With commons/lang you can do this using StringUtils.join: You can’t really beat that for brevity. Update: Re-reading this answer, I would prefer the other answer regarding Guava’s Joiner now. In fact, these days I don’t go near apache commons. Another Update: Java 8 introduced the method String.join() While this isn’t as flexible as the Guava version, it’s handy when … Read more

Converting a list to a set changes element order

A set is an unordered data structure, so it does not preserve the insertion order. This depends on your requirements. If you have an normal list, and want to remove some set of elements while preserving the order of the list, you can do this with a list comprehension:>>> a = [1, 2, 20, 6, 210] >>> … Read more

What’s the difference between HashSet and Set?

A Set represents a generic “set of values”. A TreeSet is a set where the elements are sorted (and thus ordered), a HashSet is a set where the elements are not sorted or ordered. A HashSet is typically a lot faster than a TreeSet. A TreeSet is typically implemented as a red-black tree (See – I’ve not validated the actual implementation of sun/oracle’s TreeSet), whereas a HashSet uses Object.hashCode() to create an index in … Read more

How do I add two sets?

All you have to do to combine them is Sets are unordered sequences of unique values. a | b or a.union(b) is the union of the two sets (a new set with all values found in either set). This is a class of operation called a “set operation”, which Python sets provide convenient tools for.

OpenMP set_num_threads() is not working

Besides calling omp_get_num_threads() outside of the parallel region in your case, calling omp_set_num_threads() still doesn’t guarantee that the OpenMP runtime will use exactly the specified number of threads. omp_set_num_threads() is used to override the value of the environment variable OMP_NUM_THREADS and they both control the upper limit of the size of the thread team that … Read more