Pageindexchanging which wasnt handled in c

Find centralized, trusted content and collaborate around the technologies you use most. Connect and share knowledge within a single location that is structured and easy to search. For example, I have a set, or vector, or matrix of samples A : [5, 2, 1, 4, 3]. I want to sort these to be B : [1,2,3,4,5] , but I also want to remember the original indexes of the values, so I can get another set which would be: C : [2, 1, 4, 3, 0 ] - which corresponds to the index of each element in 'B', in the original 'A'.

You could sort std::pair instead of just ints - first int is original data, second int is original index. Then supply a comparator that only sorts on the first int. Sort V and while sorting instead of comparing elements of V , compare corresponding elements of A.

Usage is the same as that of std::sort except for an index container to receive sorted indexes. I came across this question, and figured out sorting the iterators directly would be a way to sort the values and keep track of indices; There is no need to define an extra container of pair s of value, index which is helpful when the values are large objects; The iterators provides the access to both the value and the index:.

Beautiful solution by Lukasz Wiklendt! Although in my case I needed something more generic so I modified it a bit:. Example: Find indices sorting a vector of strings by length, except for the first element which is a dummy.

Consider using std::multimap as suggested by Ulrich Eckhardt. Just that the code could be made even simpler. The reason to prefer a std::multimap to a std::map is to allow equal values in original vectors. Also please note that, unlike for std::map , operator[] is not defined for std::multimap. Well, my solution uses residue technique. We can place the values under sorting in the upper 2 bytes and the indices of the elements - in the lower 2 bytes:.

After that you can access the elements' indices via residuum. The following code prints the indices of the values sorted in the ascending order:. Of course, this technique works only for the relatively small values in the original array myints i. But it has additional benefit of distinguishing identical values of myints : their indices will be printed in the right order.

Or maybe you can use a map where the key would be the element, and the values a list of its position in the upcoming arrays A, B and C. Are the items in the vector unique? If so, copy the vector, sort one of the copies with STL Sort then you can find which index each item had in the original vector. If the vector is supposed to handle duplicate items, I think youre better of implementing your own sort routine. For this type of question Store the orignal array data into a new data and then binary search the first element of the sorted array into the duplicated array and that indice should be stored into a vector or array.

Here binarysearch is a function which takes the array,size of array,searching item and would return the position of the searched item. So as you can see we define a function to call on each element before any comparaison. This projection feature is actually quite powerful since this function can be, as here, a lambda or it can even be a method, or a member value. For instance:. How are we doing? The query is not executed until you convert the IQueryable object into a collection by calling a method such as ToList.

Therefore, this code results in a single query that is not executed until the return View statement. This code uses the information in the ViewBag properties to set up hyperlinks with the appropriate query string values.

Run the page and click the Last Name and Enrollment Date column headings to verify that sorting works. After you click the Last Name heading, students are displayed in descending last name order. To add filtering to the Students index page, you'll add a text box and a submit button to the view and make corresponding changes in the Index method.

The text box lets you enter a string to search for in the first name and last name fields. The code adds a searchString parameter to the Index method. The search string value is received from a text box that you'll add to the Index view. It also adds a where clause to the LINQ statement that selects only students whose first name or last name contains the search string.

The statement that adds the Where clause executes only if there's a value to search for. In many cases you can call the same method either on an Entity Framework entity set or as an extension method on an in-memory collection. The results are normally the same but in some cases may be different. For example, the. Therefore the code in the example putting the Where statement inside an if statement makes sure that you get the same results for all versions of SQL Server.

Also, the. NET Framework implementation of the Contains method performs a case-sensitive comparison by default, but Entity Framework SQL Server providers perform case-insensitive comparisons by default. Therefore, calling the ToUpper method to make the test explicitly case-insensitive ensures that results do not change when you change the code later to use a repository, which will return an IEnumerable collection instead of an IQueryable object.

When you call the Contains method on an IEnumerable collection, you get the. NET Framework implementation; when you call it on an IQueryable object, you get the database provider implementation.

Null handling may also be different for different database providers or when you use an IQueryable object compared to when you use an IEnumerable collection. For example, in some scenarios a Where condition such as table. Run the page, enter a search string, and click Search to verify that filtering is working. Notice the URL doesn't contain the "an" search string, which means that if you bookmark this page, you won't get the filtered list when you use the bookmark.

This applies also to the column sort links, as they will sort the whole list. You'll change the Search button to use query strings for filter criteria later in the tutorial. To add paging to the Students index page, you'll start by installing the PagedList. Mvc NuGet package. Then you'll make additional changes in the Index method and add paging links to the Index view.

Mvc is one of many good paging and sorting packages for ASP. NET MVC, and its use here is intended only as an example, not as a recommendation for it over other options. The NuGet PagedList. Mvc package automatically installs the PagedList package as a dependency. The extension methods create a single page of data in a PagedList collection out of your IQueryable or IEnumerable , and the PagedList collection provides several properties and methods that facilitate paging.

The PagedList. External sorting is a term for a class of sorting algorithms that can handle massive amounts of data. External sorting is required when the data being sorted do not fit into the main memory of a computing device usually RAM and instead, they must reside in the slower external memory usually a hard drive. External sorting typically uses a hybrid sort-merge strategy. In the sorting phase, chunks of data small enough to fit in main memory are read, sorted, and written out to a temporary file.

In the merge phase, the sorted sub-files are combined into a single larger file. One example of external sorting is the external merge sort algorithm, which sorts chunks that each fit in RAM, then merges the sorted chunks together. We first divide the file into runs such that the size of a run is small enough to fit into main memory. Then sort each run in main memory using merge sort sorting algorithm. Finally merge the resulting runs together into successively bigger runs, until the file is sorted.

Inputs: Attention reader! So the data is divided into chunks and then sorted using merge sort. The sorted data is then dumped into files. As such huge amount of data cannot be handled altogether. Now After sorting the individual chunks. Sort the whole array by using the idea of merge k sorted arrays.