sort list based on another list java sort list based on another list java

All rights reserved. @RichieV I recommend using Quicksort or an in-place merge sort implementation. Why is "1000000000000000 in range(1000000000000001)" so fast in Python 3? Any suggestions? What sort of strategies would a medieval military use against a fantasy giant? The signature of the method is: T: Comparable type of element to be compared. In Java 8, stream() is an API used to process collections of objects. A tree's ordering information is irrelevant. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Zip the two lists together, sort it, then take the parts you want: Also, if you don't mind using numpy arrays (or in fact already are dealing with numpy arrays), here is another nice solution: I found it here: zip, sort by the second column, return the first column. Sorting a 10000 items list 100 times improves speed 140 times (265 ms for the whole batch instead of 37 seconds) on my unit tests. rev2023.3.3.43278. Copyright 2011-2021 www.javatpoint.com. L1-50 first, L2-50 next, then, L2-45, L2-42, L1-40 and L1-30. 12 is less than 21 and no one from L2 is in between. Do I need a thermal expansion tank if I already have a pressure tank? For more information on how to set\use the key parameter as well as the sorted function in general, take a look at this. In this case, the key extractor could be the method reference Factory::getPrice (resp. In Python 2, zip produced a list. All rights reserved. Sorry, that was my typo. - the incident has nothing to do with me; can I use this this way? Sorting values of a dictionary based on a list. How to handle a hobby that makes income in US. The signature of the method is: It also returns a stream sorted according to the provided comparator. Learn more about Stack Overflow the company, and our products. I think that the title of the original question is not accurate. Linear Algebra - Linear transformation question, Acidity of alcohols and basicity of amines, Is there a solution to add special characters from software and how to do it. 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. In this quick tutorial, we'll learn how to find items from one list based on values from another list using Java 8 Streams. That's right but the solutions use completely different methods which could be used for different applications. your map should be collected to a LinkedHashMap in order to preserve the order of listB. 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. Is there a solution to add special characters from software and how to do it. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Premium CPU-Optimized Droplets are now available. 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. Short story taking place on a toroidal planet or moon involving flying. http://scienceoss.com/sort-one-list-by-another-list/. Take a look at this solution, may be this is what you are trying to achieve: O U T P U T All times above are in ranch (not your local) time. Better example data would be quite helpful, too. Learn more. Sometimes we have to sort a list in Java before processing its elements. In the case of our integers, this means that they're sorted in ascending order. Let's start with two entity classes - Employee and Department: class Employee { Integer employeeId; String employeeName; // getters and setters } class Department { Integer . Oh, ignore, I can do sorted(zip(Index,X,Y,Z)) too. Sorting a 10000 items list 100 times improves speed 140 times (265 ms for the whole batch instead of 37 seconds) on my It's a List, and Item has a public String getWeekday() method. The solution assumes that all the objects in the list to sort have distinct keys. Sorting Strings is a tiny bit different, since it's a bit less intuitive on how to compare them. Key and Value can be of different types (eg - String, Integer). Learn the landscape of Data Visualization tools in Python - work with Seaborn, Plotly, and Bokeh, and excel in Matplotlib! However, some may lead to under-performing solutions if not done properly. I am a bit confused with FactoryPriceComparator class. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If so, how close was it? The best answers are voted up and rise to the top, Not the answer you're looking for? Assume that the dictionary and the words only contain lowercase alphabets. 2) Does listA and listB contain references to the same objects, or just objects that are equivalent with equals()? Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. As each pair of strings are passed in for comparison, convert them into ints using originalList.indexOf, except that if the index is -1, change the index to originalList.size() Compare the two ints. Why is this sentence from The Great Gatsby grammatical? Then we sort the list. I think most of the solutions above will not work if the 2 lists are of different sizes or contain different items. Making statements based on opinion; back them up with references or personal experience. In our case, we're using the getAge() method as the sorting key. MathJax reference. - Hatefiend Unsubscribe at any time. There are two simple ways to do this - supply a Comparator, and switch the order, which we'll cover in a later section, or simply use Collections.reverseOrder() in the sorted() call: Though, we don't always just sort integers. Using Comparator. HashMap entries are sorted according to String value. Asking for help, clarification, or responding to other answers. @Jack Yes, like what I did in the last example. We can use the following methods to sort the list: Using stream.sorted () method Using Comparator.reverseOrder () method Using Comparator.naturalOrder () method Using Collections.reverseOrder () method Using Collections.sort () method Java Stream interface Java Stream interface provides two methods for sorting the list: sorted () method The most obvious solution to me is to use the key keyword arg. Has 90% of ice around Antarctica disappeared in less than a decade? Key Selector Variant. Linear regulator thermal information missing in datasheet, How to tell which packages are held back due to phased updates. Just encountered the same problem. How do I call one constructor from another in Java? Does this assume that the lists are of same size? that requires an extra copy, but I think to to it in place is a lot less efficient, and all kinds of not clear: Note I didn't test either, maybe got a sign flipped. The solution below is simple and should fix those issues: Location of index in list2 is tracked using cur_loclist. The order of the elements having the same "key" does not matter. Is there a solution to add special characters from software and how to do it. Using Kolmogorov complexity to measure difficulty of problems? Connect and share knowledge within a single location that is structured and easy to search. It throws NullPointerException when comparing null. I like having a list of sorted indices. Excuse any terrible practices I used while writing this code, though. There are others concerns with your code, without going into the sort: getCompetitors() returns directly the internal list stored by your factory object. 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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. How can I pair socks from a pile efficiently? Your problem statement is not very clear. That way, I can sort any list in the same order as the source list. 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. So in a nutshell, we can sort a list by simply calling: java.util.Collections.sort(the list) as shown in the following example: The above class creates a list of four integers and, using the collection sort method, sorts this list (in one line of code) without us having to worry about the sorting algorithm. How do you get out of a corner when plotting yourself into a corner. You should instead use [x for (y,x) in sorted(zip(Y,X), key=lambda pair: pair[0])]. There are plenty of ways to achieve this. We've used the respective comparison approaches for the names and ages - comparing names lexicographically using compareTo(), if the age values are the same, and comparing ages regularly via the > operator. 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. In each iteration, follow the following step . 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. Check out our offerings for compute, storage, networking, and managed databases. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? Here is my complete code to achieve this result: But, is there another way to do it? good solution! IMO, you need to persist something else. Created a default comparator on bookings to sort the list. This will provide a quick and easy lookup. O(n) look up happening roughly O(nlogn) times? His title should have been 'How to sort a dictionary?'. The size of both list must be same to use this trick. Check out our offerings for compute, storage, networking, and managed databases. 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. 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. It puts the capital letter elements first in natural order after that small letters in the natural order, if the list has both small and capital letters. Sorting list according to corresponding values from a parallel list [duplicate]. you can leverage that solution directly in your existing df. 2. Rather than using a list to get values from the map, well be using LinkedHashMap to create the sorted hashmap directly. 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. The returned comparable is serializable. We can use Collections.sort() method to sort a list in the natural ascending order. What is the shortest way of sorting X using values from Y to get the following output? This trick will never fails and ensures the mapping between the items in list. People will search this post looking to sort lists not dictionaries. then the question should be 'How to sort a dictionary? It seems what you want would be to use Comparable instead, but even this isn't a good idea in this case. I have created a more general function, that sorts more than two lists based on another one, inspired by @Whatang's answer. We can use the following methods to sort the list: Java Stream interface provides two methods for sorting the list: Stream interface provides a sorted() method to sort a list. DigitalOcean makes it simple to launch in the cloud and scale up as you grow whether youre running one virtual machine or ten thousand. JavaTpoint offers college campus training on Core Java, Advance Java, .Net, Android, Hadoop, PHP, Web Technology and Python. 2. :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 . If you have 2 lists of identical number of items and where every item in list 1 is related to list 2 in the same order (e.g a = 0 , b = 1, etc.) The solution below is simple and should fix those issues: Location of index in list2 is tracked using cur_loclist. You return. Making statements based on opinion; back them up with references or personal experience. Then when you initialise your Comparator, pass in the list used for ordering. It is from Java 8. Also easy extendable for similar problems! To get a value from the HashMap, we use the key corresponding to that entry. To avoid having a very inefficient look up, you should index the items in listB and then sort listA based on it. For cases like these, we'll want to write a custom Comparator: And now, when we execute this code, we've got the natural order of names, as well as ages, sorted: Here, we've used a Lambda expression to create a new Comparator implicitly and defined the logic for sorting/comparison. Assuming that the larger list contains all values in the smaller list, it can be done. Lets look at an example where our value is a custom object. HashMap in java provides quick lookups. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sort a list of Object according to custom priority of value in the Object JAVA 11, sort list of object on java 8 with custom criteria, Sort list based on specific order in java, (Java) Using lambda as comparator in Arrays.sort, How can I sort a list based on another list values in Java, Android Java - I need to sort a list based on another list, Intersection and union of ArrayLists in Java. . I used java 8 streams to sort lists and put them in ArrayDeques. The source of these elements is usually a Collection or an Array, from which data is provided to the stream. http://scienceoss.com/sort-one-list-by-another-list/. - the incident has nothing to do with me; can I use this this way? This tutorial covered sorting of HashMap according to Value. 3.1. Not the answer you're looking for? "Sunday" => 0, , "Saturday" => 6. The solution below is simple and does not require any imports. I mean swapItems(), removeItem(), addItem(), setItem() ?? Why is this sentence from The Great Gatsby grammatical? 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. May be just the indexes of the items that the user changed. zip, sort by the second column, return the first column. 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. 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. Learn more about Stack Overflow the company, and our products. The preferred way to add something to SortedDependingList is by already knowing the index of an element and adding it by calling sortedList.addByIndex(index); If the two lists are guaranteed to contain the same elements, just in a different order, you can use List listA = new ArrayList<>(listB) and this will be O(n) time complexity. Acidity of alcohols and basicity of amines. Using Java 8 Streams. The solution below is simple and does not require any imports. 2. We can sort a list in natural ordering where the list elements must implement Comparable interface. How to use Slater Type Orbitals as a basis functions in matrix method correctly? B:[2,1,0], And you want to load them both and then produce: Connect and share knowledge within a single location that is structured and easy to search. I like this because I can do multiple lists with one index. You are using Python 3. Let's look at the code. [[name=a, age=age11], [name=a, age=age111], [name=a, age=age1], [name=b, age=age22], [name=b, age=age2], [name=c, age=age33], [name=c, age=age3]]. Thanks for contributing an answer to Code Review Stack Exchange! Streams differ from collections in several ways; most notably in that the streams are not a data structure that stores elements. I fail to see where the problem is. - the incident has nothing to do with me; can I use this this way? Lets look at a quick example to sort a list of strings. How do I sort a list of dictionaries by a value of the dictionary? Premium CPU-Optimized Droplets are now available. The method signature is: Comparable is also an interface belong to a java.lang package. Working on improving health and education, reducing inequality, and spurring economic growth? This is actually the proper way of doing it: when you sort a Factory, you cannot sort the inner competitors at the same time, because different objects are being compared. This method returns a lexicographic-order comparator with another comparator. If the data is related then the data should be stored together in a simple class. Wed like to help. Linear Algebra - Linear transformation question. super T> comparator), Defining a Custom Comparator with Stream.sorted(). You can have an instance of the comparator (let's call it, @BrunoCosta Correct, I assumed it wasn't readonly since the OP called, Sorting a list and another list inside each item, How Intuit democratizes AI development across teams through reusability. You are using Python 3. The signature of the method is: In the following example, we have used the following methods: The reverseOrder() is a method of Comparator interface which is defined in java.util package. You get paid; we donate to tech nonprofits. 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. How can this new ban on drag possibly be considered constitutional? Let's say you have a listB list that defines the order in which you want to sort listA. ', not 'How to sorting list based on values from another list?'. 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. Thanks for contributing an answer to Code Review Stack Exchange! For example, when appendFirst is false below will be the output.