sort list based on another list java

@RichieV I recommend using Quicksort or an in-place merge sort implementation. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. Although I am not entirely sure exactly what the OP is asking for, I couldn't help but come to this conclusion as well. How do you ensure that a red herring doesn't violate Chekhov's gun? It returns a comparator that imposes reverse of the natural ordering. That's easily managed with an index list: Since the decorate-sort-undecorate approach described by Whatang is a little simpler and works in all cases, it's probably better most of the time. This solution is poor when it comes to storage. Examples: Input: words = {"hello", "geeksforgeeks"}, order = "hlabcdefgijkmnopqrstuvwxyz" Output: "hello", "geeksforgeeks" Explanation: So for me the requirement was to sort originalList with orderedList. @Hatefiend interesting, could you point to a reference on how to achieve that? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Found within the Stream interface, the sorted() method has two overloaded variations that we'll be looking into. You are using Python 3. What happens if you have in List1, 50, 40 30 , and in List2 50 45 42? It also doesn't care if the List R you want to sort contains Comparable elements so long as the other List L you use to sort them by is uniformly Comparable. You can use this generic comparator to sort list based on the the other list. That way, I can sort any list in the same order as the source list. Now it produces an iterable object. The below example demonstrates the concept of How to sort the List in Java 8 using Lambda Expression. If you're not used to Lambda expressions, you can create a Comparator beforehand, though, for the sake of code readability, it's advised to shorten it to a Lambda: You can also technically make an anonymous instantiation of the comparator in the sorted() call: And this anonymous call is exactly what gets shortened to the Lambda expression from the first approach. Does Counterspell prevent from any further spells being cast on a given turn? The signature of the method is: It also returns a stream sorted according to the provided comparator. 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Sorting a Java list collection using Lambda expression Since Java 8 with Lambda expressions support, we can write a comparator in a more concise way as follows: 1 Comparator<Book> descPriceComp = (Book b1, Book b2) -> (int) (b2.getPrice () - b1.getPrice ()); 12 is less than 21 and no one from L2 is in between. Merge two lists in Java and sort them using Object property and another condition, How Intuit democratizes AI development across teams through reusability. More general case (sort list Y by any key instead of the default order), http://scienceoss.com/sort-one-list-by-another-list/, How Intuit democratizes AI development across teams through reusability. We can also pass a Comparator implementation to define the sorting rules. The Collections class has two methods for sorting a list: The sort() method sorts the list in ascending order, according to the natural ordering of its elements. Theoretically Correct vs Practical Notation, Bulk update symbol size units from mm to map units in rule-based symbology. Better example data would be quite helpful, too. This can be elegantly solved with guava's Ordering.explicit: The last version of Guava thas supports Java 6 is Guava 20.0: First create a map, with sortedItem.name to its first index in the list. You get paid; we donate to tech nonprofits. His title should have been 'How to sort a dictionary?'. Learn more about Stack Overflow the company, and our products. Whats the grammar of "For those whose stories they are"? In the case of our integers, this means that they're sorted in ascending order. More elegant code or using some built in Java class? Let's look at the code. For more information on how to set\use the key parameter as well as the sorted function in general, take a look at this. This solution is poor when it comes to storage. In this tutorial, we will learn how to sort a list in the natural order. For example, when appendFirst is false below will be the output. Sorting list according to corresponding values from a parallel list [duplicate]. This class has two parameters, firstName and lastName. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Let's define a User class, which isn't Comparable and see how we can sort them in a List, using Stream.sorted(): In the first iteration of this example, let's say we want to sort our users by their age. How can we prove that the supernatural or paranormal doesn't exist? Note: Any item not in list1 will be ignored since the algorithm will not know what's the sort order to use. We will use a simple sorting algorithm, Bubble Sort, to sort the elements of a linked list in ascending order below. How is an ETF fee calculated in a trade that ends in less than a year? Making statements based on opinion; back them up with references or personal experience. Note that the class must implement Comparable interface. @RichieV I recommend using Quicksort or an in-place merge sort implementation. Sometimes we have to sort a list in Java before processing its elements. Did you try it with the sample lists. But it should be: The list is ordered regarding the first element of the pairs, and the comprehension extracts the 'second' element of the pairs. Most of the solutions above are complicated and I think they will not work if the lists are of different lengths or do not contain the exact same items. People will search this post looking to sort lists not dictionaries. Sorting a 10000 items list 100 times improves speed 140 times (265 ms for the whole batch instead of 37 seconds) on my more_itertools has a tool for sorting iterables in parallel: I actually came here looking to sort a list by a list where the values matched. I mean swapItems(), removeItem(), addItem(), setItem() ?? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Here if the data type of Value is String, then we sort the list using a comparator. Your compare methods are currently doing: This can be written more concisely with the built-in Double.compare (since Java 7), which also properly handles NaN, -0.0 and 0.0, contrary to your current code: Note that you would have the same implementation for the Comparator. You posted your solution two times. The java.Collections.sort () method sorts the list elements by comparing the ASCII values of the elements. Once we have the list of values in a sorted manner, we build the HashMap again based on this new list. This trick will never fails and ensures the mapping between the items in list. . It only takes a minute to sign up. I have a list of ordered keys, and I need to order the objects in a list according to the order of the keys. Let's save this result into a sortedList: Here we see that the original list stayed unmodified, but we did save the results of the sorting in a new list, allowing us to use both if we need so later on. 1. Other answers didn't bother to import operator and provide more info about this module and its benefits here. rev2023.3.3.43278. Asking for help, clarification, or responding to other answers. You can setup history as a HashMap or separate class to make this easier. If the list is less than 3 do nothing. rev2023.3.3.43278. http://scienceoss.com/sort-one-list-by-another-list/. While we believe that this content benefits our community, we have not yet thoroughly reviewed it. MathJax reference. Thanks for learning with the DigitalOcean Community. We can easily reverse this order as well, simply by chaining the reversed() method after the comparingInt() call: While Comparators produced by methods such as comparing() and comparingInt(), are super-simple to work with and only require a sorting key - sometimes, the automated behavior is not what we're looking for. When we try to use sort over a zip object. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This method will also work when both lists are not identical: /** * Sorts list objectsToOrder based on the order of orderedObjects. Each factory has an item of its own and a list of other items from competitors. MathJax reference. A:[c,b,a] The java.Collections.sort () method is also used to sort the linked list, array, queue, and other data structures. We first get the String values in a list. We can also pass a Comparator implementation to define the sorting rules. Also easy extendable for similar problems! Not the answer you're looking for? Then, yep, you need to loop through them and sort the competitors. Returning a positive number indicates that an element is greater than another. I have a list of factories. When we compare null, it throws NullPointerException. As you can see from the output, the linked list elements are sorted in ascending order by the sort method. I want to sort listA based on listB. Developed by JavaTpoint. - Hatefiend Specifically, we're using the comparingInt() method, and supplying the user's age, via the User::getAge method reference. You can have an instance of the comparator (let's call it factoryPriceComparator) and use it like: Collections.sort (factoriesList, factoryPriceComparator);. Designed by Colorlib. Ultimately, you can also just use the comparing() method, which accepts a sorting key function, just like the other ones. Get tutorials, guides, and dev jobs in your inbox. You can implement a custom Comparator to sort a list by multiple attributes. The Comparator.comparing () method accepts a method reference which serves as the basis of the comparison. It is the method of Java Collections class which belong to a java.lang package. We can sort the entries in a HashMap according to keys as well as values. The collect() method is used to receive elements from a stream and stored them in a collection. Acidity of alcohols and basicity of amines. Sort an array according to the order defined by another array using Sorting and Binary Search: The idea is to sort the A1 [] array and then according to A2 [] store the elements. You can checkout more examples from our GitHub Repository. I like having a list of sorted indices. The solution below is the most efficient in this case: Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Follow Up: struct sockaddr storage initialization by network format-string. See JB Nizet's answer for an example of a custom Comparator that does this. This can create unstable outputs unless you include the original list indices for the lexicographic ordering to keep duplicates in their original order. What sort of strategies would a medieval military use against a fantasy giant? That's right but the solutions use completely different methods which could be used for different applications. Overview Filtering a Collection by a List is a common business logic scenario. To place them last, you can use a nullsLast comparator: I would just use a map with indexes of each name, to simplify the lookup: Then implement a Comparator that sorts by looking up names in indexOfMap: Note that the order of the first elements in the resulting list is not deterministic (because it's just all elements not present in list2, with no further ordering). Why do academics stay as adjuncts for years rather than move around? If a law is new but its interpretation is vague, can the courts directly ask the drafters the intent and official interpretation of their law? good solution! In java 6 or lower, you need to use. We can sort a list in natural ordering where the list elements must implement Comparable interface. 1. All the elements in the list must implement Comparable interface, otherwise IllegalArgumentException is thrown. Let the size of A1 [] be m and the size of A2 [] be n. Create a temporary array temp of size m and copy the contents of A1 [] to it. "After the incident", I started to be more careful not to trip over things. Once you have that, define your own comparison function which compares values based on the indexes of list Y. Using Java 8 Streams Let's start with two entity classes - Employee and Department: The . We can also create a custom comparator to sort the hash map according to values. We are sorting the names according to firstName, we can also use lastName to sort. Python. Note that you can shorten this to a one-liner if you care to: As Wenmin Mu and Jack Peng have pointed out, this assumes that the values in X are all distinct. Sorting a List of Integers with Stream.sorted () Found within the Stream interface, the sorted () method has two overloaded variations that we'll be looking into. How can I randomly select an item from a list? You are using Python 3. Once streamed, we can run the sorted() method, which sorts these integers naturally. Making statements based on opinion; back them up with references or personal experience. Did you try it with the sample lists. More general case (sort list Y by any key instead of the default order), http://scienceoss.com/sort-one-list-by-another-list/, How Intuit democratizes AI development across teams through reusability. Then when you initialise your Comparator, pass in the list used for ordering. Is the God of a monotheism necessarily omnipotent? We can sort a list in natural ordering where the list elements must implement Comparable interface. To get a value from the HashMap, we use the key corresponding to that entry. There are at least two good idioms for this problem. There is a difference between the two: a class is Comparable when it can compare itself to another class of the same type, which is what you are doing here: one Factory is comparing itself to another object. Linear regulator thermal information missing in datasheet, Short story taking place on a toroidal planet or moon involving flying, Identify those arcade games from a 1983 Brazilian music video, It is also probably wrong to have your class implements. However, if we're working with some custom objects, which might not be Comparable by design, and would still like to sort them using this method - we'll need to supply a Comparator to the sorted() call. zip, sort by the second column, return the first column. This gives you more direct control over how to sort the input, so you can get sorting stability by simply stating the specific key to sort by. Sorting values of a dictionary based on a list. Once sorted, we've just printed them out, each in a line: If we wanted save the results of sorting after the program was executed, we would have to collect() the data back in a Collection (a List in this example), since sorted() doesn't modify the source. Note: The LinkedList elements must implement the Comparable interface for this method to work. Connect and share knowledge within a single location that is structured and easy to search. The Collections (Java Doc) class (part of the Java Collection Framework) provides a list of static methods which we can use when working with collections such as list, set and the like. If the age of the users is the same, the first one that was added to the list will be the first in the sorted order. A tree illustrates a hierarchical structure in contrast to other data structures such an array, stack, queue, and linked list, which are linear in nature. In each iteration, follow the following step . Let's say we have the following code: Let's sort them by age, first. This could be done by wrapping listA inside a custom sorted list like so: Then you can use this custom list as follows: Of course, this custom list will only be valid as long as the elements in the original list do not change. This comparator sorts the list of values alphabetically. How to handle a hobby that makes income in US. Find centralized, trusted content and collaborate around the technologies you use most. By default, the sort () method sorts a given list into ascending order (or natural order ). Basically, this answer is nonsense. Python. If you want to do it manually. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Why is this sentence from The Great Gatsby grammatical? If a law is new but its interpretation is vague, can the courts directly ask the drafters the intent and official interpretation of their law? - the incident has nothing to do with me; can I use this this way? Though it might not be obvious, this is exactly equivalent to, This is correct, but I'll add the note that if you're trying to sort multiple arrays by the same array, this won't neccessarily work as expected, since the key that is being used to sort is (y,x), not just y. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Sorting list based on another list's order. All of them simply return a comparator, with the passed function as the sorting key. Can you write oxidation states with negative Roman numerals? Is it possible to create a concave light? Note: the key=operator.itemgetter(1) solves the duplicate issue, zip is not subscriptable you must actually use, If there is more than one matching it gets the first, This does not solve the OPs question. ', not 'How to sorting list based on values from another list?'. I have created a more general function, that sorts more than two lists based on another one, inspired by @Whatang's answer. Here's a simple implementation of that logic. Using Kolmogorov complexity to measure difficulty of problems? My use case is this: user has a list of items initially (listA). If they are already numpy arrays, then it's simply. :param lists: lists to be sorted :return: a tuple containing the sorted lists """ # Create the initially empty lists to later store the sorted items sorted_lists = tuple([] for _ in range(len(lists))) # Unpack the lists, sort them, zip them and iterate over them for t in sorted(zip(*lists)): # list items are now sorted based on the first list . Collections.sort() method is overloaded and we can also provide our own Comparator implementation for sorting rules. 1. Otherwise, I see a lot of answers here using Collections.sort(), however there is an alternative method which is guaranteed O(2n) runtime, which should theoretically be faster than sort's worst time complexity of O(nlog(n)), at the cost of 2n storage. Solution based on bubble sort (same length required): If the object references should be the same, you can initialize listA new. 2. A example will show this. In Python 2, zip produced a list. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Like Tim Herold wrote, if the object references should be the same, you can just copy listB to listA, either: Or this if you don't want to change the List that listA refers to: If the references are not the same but there is some equivalence relationship between objects in listA and listB, you could sort listA using a custom Comparator that finds the object in listB and uses its index in listB as the sort key. How to make it come last.? How do you get out of a corner when plotting yourself into a corner, Trying to understand how to get this basic Fourier Series. We can use this by creating a list of Integers and sort these using the Collections.sort(). originalList always contains all element from orderedList, but not vice versa. String values require a comparator for sorting. I suspect the easiest way to do this will be by writing a custom implementation of java.util.Comparator which can be used in a call to Collections.sort(). This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. HashMap in java provides quick lookups. rev2023.3.3.43278. We're streaming that list, and using the sorted() method with a Comparator. Copyright 2011-2021 www.javatpoint.com. Here is Whatangs answer if you want to get both sorted lists (python3). Why do academics stay as adjuncts for years rather than move around? Note that you can shorten this to a one-liner if you care to: As Wenmin Mu and Jack Peng have pointed out, this assumes that the values in X are all distinct. One way of doing this is looping through listB and adding the items to a temporary list if listA contains them: Not completely clear what you want, but if this is the situation: That is, the first items (from Y) are compared; and if they are the same then the second items (from X) are compared, and so on. It is from Java 8. What I am doing require to sort collection of factories and loop through all factories and sort collection of their competitors. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. I see where you are going with it, but you need to rethink what you were going for and edit this answer. Getting key with maximum value in dictionary? I think most of the solutions above will not work if the 2 lists are of different sizes or contain different items. The Comparator.comparing static function accepts a sort key Function and returns a Comparator for the type that contains the sort key: To see this in action, we'll use the name field in Employee as the sort key, and pass its method reference as an argument of type Function. That's easily managed with an index list: Since the decorate-sort-undecorate approach described by Whatang is a little simpler and works in all cases, it's probably better most of the time. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sorting a list in Python using the result from sorting another list, How to rearrange one list based on a second list of indices, How to sort a list according to another list? To learn more, see our tips on writing great answers. We can now eliminate the anonymous inner class and achieve the same result with simple, functional semantics using lambdas: (Employee e1, Employee e2) -> e1.getName ().compareTo (e2.getName ()); We can test it as below: Speed improvement on JB Nizet's answer (from the suggestion he made himself). - the incident has nothing to do with me; can I use this this way? The method returns a comparator that compares Comparable objects in the natural order. I can resort to the use of for constructs but I am curious if there is a shorter way. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Linear regulator thermal information missing in datasheet. If you have any suggestions for improvements, please let us know by clicking the report an issue button at the bottom of the tutorial. Use MathJax to format equations. They reorder the items and want to persist that order (listB), however, due to restrictions I'm unable persist the order on the backend so I have to sort listA after I retrieve it. If changes are possible, you would need to somehow listen for changes to the original list and update the indices inside the custom list. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? B:[2,1,0], And you want to load them both and then produce: Else, run a loop till the last node (i.e. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? How do you get out of a corner when plotting yourself into a corner. Republic Services Bulk Pickup Schedule, Articles S