A one-liner splitting d into chunks of size 20: split(d, ceiling(seq_along(d)/20)) More details: I think all you need is seq_along(), split() and ceiling(): > d <- rpois(73,5) > d [1] 3 1 11 4 1 2 3 2 4 10 10 2 7 4 6 6 2 1 1 2 3 8 3 10 7 … Read more
Use the remove/erase idiom: std::vector<int>& vec = myNumbers; // use shorter name vec.erase(std::remove(vec.begin(), vec.end(), number_in), vec.end()); What happens is that remove compacts the elements that differ from the value to be removed (number_in) in the beginning of the vector and returns the iterator to the first element after that range. Then erase removes these elements … Read more
If you have a C++11 compiler, I would suggest using a range-based for-loop (see below); or else use an iterator. But you have several options, all of which I will explain in what follows. range-based for-loop (C++11) In C++11 (and later) you can use the new range-based for-loop, which looks like this: std::vector<char> path; // … Read more
Consider whether you really need all this data explicitly, or can the matrix be sparse? There is good support in R (see Matrix package for e.g.) for sparse matrices. Keep all other processes and objects in R to a minimum when you need to make objects of this size. Use gc() to clear now unused … Read more
Vector synchronizes on each individual operation. That’s almost never what you want to do. Generally you want to synchronize a whole sequence of operations. Synchronizing individual operations is both less safe (if you iterate over a Vector, for instance, you still need to take out a lock to avoid anyone else changing the collection at … Read more
You chould exchange conditions in the while statement while ( i < arr.size() && a != arr[i] ) i++; Also this condition is wrong while(!text.eof()) { text>>a; The eof state can occur after statement text>>a; in the block of the while. Change it to while ( text >> a )
When you do v1.insert(v1.begin(), 7), you are just inserting an element at the beginning of v1. You don’t expect that, after inserting an element, the number of elements stays the same. I think what you want is simply v1[0] = 7.
did I build a 7 dimensional vector in this way? Yes you have. A vector is a way of storing a magnitude and direction, which is done by correctly assigning the value and sign of each double. A vector in 2-space would require two values, and a vector in 7-space would require 7 values, which … Read more
If you want to make an array of vectors while reading it’s size from a file you have to do this: int size; in>>size; vector<A>[size] vector_array; I’m not sure what you want. If you want to read it’s value from a file you can do this: for(int i = 0;i<array.size();i++){ //get data from file and … Read more
First, you will need to push your prime numbers in the vector. At the beginning, unless you ask otherwise, the vector is empty. You can push a prime number using this snippet: // somewhere you declare your vector std::vector<unsigned long long> primes; // code computing a prime number unsigned long long prime; …. // Push … Read more