From C++11 onwards, you should prefer: #include <algorithm> #include <random> auto rng = std::default_random_engine {}; std::shuffle(std::begin(cards_), std::end(cards_), rng); Live example on Coliru Make sure to reuse the same instance of rng throughout multiple calls to std::shuffle if you intend to generate different permutations every time! Moreover, if you want your program to create different sequences … Read more
A good linear-time shuffling algorithm is the Fisher-Yates shuffle. One problem you’ll find with your proposed algorithm is that as you near the end of the shuffle, your loop will spend a lot of time looking for randomly chosen elements that have not yet been swapped. This may take an indeterminate amount of time once … Read more
random.shuffle() changes the x list in place. Python API methods that alter a structure in-place generally return None, not the modified data structure. >>> x = [‘foo’, ‘bar’, ‘black’, ‘sheep’] >>> random.shuffle(x) >>> x [‘black’, ‘bar’, ‘sheep’, ‘foo’] If you wanted to create a new randomly-shuffled list based on an existing one, where the existing … Read more
After Jon has already covered the theory, here’s an implementation: function shuffle(array) { var tmp, current, top = array.length; if(top) while(–top) { current = Math.floor(Math.random() * (top + 1)); tmp = array[current]; array[current] = array[top]; array[top] = tmp; } return array; } The algorithm is O(n), whereas sorting should be O(n log n). Depending on … Read more
random.shuffle should work. Here’s an example, where the objects are lists: from random import shuffle x = [[i] for i in range(10)] shuffle(x) # print(x) gives [[9], [2], [7], [0], [4], [5], [3], [1], [8], [6]] # of course your results will vary Note that shuffle works in place, and returns None.
I solved this by adding a category to NSMutableArray. Edit: Removed unnecessary method thanks to answer by Ladd. Edit: Changed (arc4random() % nElements) to arc4random_uniform(nElements) thanks to answer by Gregory Goltsov and comments by miho and blahdiblah Edit: Loop improvement, thanks to comment by Ron Edit: Added check that array is not empty, thanks to … Read more
It’s not a way of shuffling that I like, mostly on the grounds that it’s O(n log n) for no good reason when it’s easy to implement an O(n) shuffle. The code in the question “works” by basically giving a random (hopefully unique!) number to each element, then ordering the elements according to that number. … Read more
This answer details how to shuffle with a fast and uniform algorithm (Fisher-Yates) in Swift 4.2+ and how to add the same feature in the various previous versions of Swift. The naming and behavior for each Swift version matches the mutating and nonmutating sorting methods for that version. Swift 4.2+ shuffle and shuffled are native … Read more
Random shuffling of an array