nth-element

Does C# have a std::nth_element equivalent?

由 别来无恙 提交于 2020-01-10 04:51:05
问题 I'm porting some C++ code to C#. Does C# have an equivalent to std::nth_element() or do I need to roll my own? 回答1: I presume you are looking for an accessor that returns the Nth element of an unordered collection by performing a partial-sort on the collection. This tends to be useful when you have a very large collection and are interested in one of the first elements based on some ordering predicate. To my knowledge, neither the .NET BCL or LINQ extensions offer an equivalent. All of the

How is nth_element Implemented?

由 送分小仙女□ 提交于 2019-12-31 10:52:46
问题 There are a lot of claims on StackOverflow and elsewhere that nth_element is O(n) and that it is typically implemented with Introselect: http://en.cppreference.com/w/cpp/algorithm/nth_element I want to know how this can be achieved. I looked at Wikipedia's explanation of Introselect and that just left me more confused. How can an algorithm switch between QSort and Median-of-Medians? I found the Introsort paper here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.14.5196&rep=rep1

How is nth_element Implemented?

由 寵の児 提交于 2019-12-31 10:49:17
问题 There are a lot of claims on StackOverflow and elsewhere that nth_element is O(n) and that it is typically implemented with Introselect: http://en.cppreference.com/w/cpp/algorithm/nth_element I want to know how this can be achieved. I looked at Wikipedia's explanation of Introselect and that just left me more confused. How can an algorithm switch between QSort and Median-of-Medians? I found the Introsort paper here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.14.5196&rep=rep1

How is nth_element Implemented?

由 心不动则不痛 提交于 2019-12-31 10:49:10
问题 There are a lot of claims on StackOverflow and elsewhere that nth_element is O(n) and that it is typically implemented with Introselect: http://en.cppreference.com/w/cpp/algorithm/nth_element I want to know how this can be achieved. I looked at Wikipedia's explanation of Introselect and that just left me more confused. How can an algorithm switch between QSort and Median-of-Medians? I found the Introsort paper here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.14.5196&rep=rep1

finding quartiles

由 拟墨画扇 提交于 2019-12-19 06:03:38
问题 I've written a program where the user can enter any number of values into a vector and it's supposed to return the quartiles, but I keep getting a "vector subscript out of range" error : #include "stdafx.h" #include <iostream> #include <string> #include <algorithm> #include <iomanip> #include <ios> #include <vector> int main () { using namespace std; cout << "Enter a list of numbers: "; vector<double> quantile; double x; //invariant: homework contains all the homework grades so far while (cin

algorithm for nth_element [closed]

由 断了今生、忘了曾经 提交于 2019-12-18 02:02:13
问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 6 years ago . I have recently found out that there exists a method called nth_element in the STL. To quote the description: Nth_element is similar to partial_sort, in that it partially orders a range of elements: it arranges the range [first, last) such that the element pointed to by the

Calling std::nth_element() function extremely frequently

由 爷，独闯天下 提交于 2019-12-04 17:30:01
问题 I did not find this specific topic anywhere... I am calling the nth_element() algorithm about 400,000 times per second on different data in a std::vector of 23 integers, more precise "unsigned short" values. I want to improve computation speed and this particular call needs a significant portion of CPU time. Now I noted, as with std::sort(), that the nth_element function is visible in the profiler even with highest optimisation level and NDEBUG mode (Linux Clang compiler), so the comparison

Calling std::nth_element() function extremely frequently

由 天涯浪子 提交于 2019-12-03 10:27:38
I did not find this specific topic anywhere... I am calling the nth_element() algorithm about 400,000 times per second on different data in a std::vector of 23 integers, more precise "unsigned short" values. I want to improve computation speed and this particular call needs a significant portion of CPU time. Now I noted, as with std::sort(), that the nth_element function is visible in the profiler even with highest optimisation level and NDEBUG mode (Linux Clang compiler), so the comparison is inlined but not the function call itself. Well, more preise: not nth_element() but std::__introselect
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