Merge two lists in Java and sort them using Object property and another condition, How Intuit democratizes AI development across teams through reusability. In addition, the proposed solution won't work for the initial question as the lists X and Y contain different entries. 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. When we try to use sort over a zip object. Replacing broken pins/legs on a DIP IC package. 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. We've sorted Comparable integers and Strings, in ascending and descending order, as well as used a built-in Comparator for custom objects. You should instead use [x for (y,x) in sorted(zip(Y,X), key=lambda pair: pair[0])]. So basically, I have 2 ArrayLists (listA and listB). ', not 'How to sorting list based on values from another list?'. "After the incident", I started to be more careful not to trip over things. good solution! The answer of riza might be useful when plotting data, since zip(*sorted(zip(X, Y), key=lambda pair: pair[0])) returns both the sorted X and Y sorted with values of X. 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. rev2023.3.3.43278. How do you ensure that a red herring doesn't violate Chekhov's gun? This is generally not a good idea: it means a client of Factory can modify its internal structure, which defeats the OOP principle. As I understand it, you want to have a combined sorted list but interleave elements from list1 and list2 whenever the age is the same. 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. 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. There are others concerns with your code, without going into the sort: getCompetitors() returns directly the internal list stored by your factory object. How To Install Grails on an Ubuntu 12.04 VPS, Simple and reliable cloud website hosting, New! Stop Googling Git commands and actually learn it! May be not the full listB, but something. 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. Returning a positive number indicates that an element is greater than another. Is the God of a monotheism necessarily omnipotent? Here is my complete code to achieve this result: But, is there another way to do it? This trick will never fails and ensures the mapping between the items in list. In case of Strings, they're sorted lexicographically: If we wanted the newly sorted list saved, the same procedure as with the integers applies here: Check out our hands-on, practical guide to learning Git, with best-practices, industry-accepted standards, and included cheat sheet. http://scienceoss.com/sort-one-list-by-another-list/. zip, sort by the second column, return the first column. How Intuit democratizes AI development across teams through reusability. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. All rights reserved. Read our Privacy Policy. 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. JavaTpoint offers college campus training on Core Java, Advance Java, .Net, Android, Hadoop, PHP, Web Technology and Python. The signature of the method is: T: Comparable type of element to be compared. Option 3: List interface sort () [Java 8] Java 8 introduced a sort method in the List interface which can use a comparator. No spam ever. You get paid; we donate to tech nonprofits. Thanks for learning with the DigitalOcean Community. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Sign up for Infrastructure as a Newsletter. 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. #kkjavatutorials #JavaAbout this Video:Hello Friends,In this video,we will talk and learn about How to Write a Java program for Sort Map based on Values (Cus. 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). Sorting for String values differs from Integer values. We're streaming that list, and using the sorted() method with a Comparator. Here is an example of how to sort a list and then make the changes in another list according to the changes exactly made to first array list. The signature of the method is: Let's see another example of Collections.sorts() method. Key Selector Variant. Here, the sorted() method also follows the natural order, as imposed by the JVM. 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. test bed for array based list implementation, Reading rows based on column value in POI. Solution based on bubble sort (same length required): If the object references should be the same, you can initialize listA new. Here if the data type of Value is String, then we sort the list using a comparator. Lets look at an example where our value is a custom object. Python. Please mail your requirement at [emailprotected] Duration: 1 week to 2 week. That's O(n^2 logn)! On the other hand, a Comparator is a class that is comparing 2 objects of the same type (it does not compare this with another object). To sort the String values in the list we use a comparator. 1. 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 ()); Find the max recommended item from second sublist (3 to end of list) and add it to the newly created list and . I like this because I can do multiple lists with one index. Short story taking place on a toroidal planet or moon involving flying. If you notice the above examples, the Value objects implement the Comparator interface. This is an old question but some of the answers I see posted don't actually work because zip is not scriptable. Do roots of these polynomials approach the negative of the Euler-Mascheroni constant? Theoretically Correct vs Practical Notation, Bulk update symbol size units from mm to map units in rule-based symbology. The sort method orders the elements in their natural order which is ascending order for the type Integer.. This solution is poor when it comes to storage. How to sort one list and re-sort another list keeping same relation python? I am also wandering if there is a better way to do that. I think that the title of the original question is not accurate. 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. I can resort to the use of for constructs but I am curious if there is a shorter way. Note also, that the SortedDependingList does currently not allow to add an element from listA a second time - in this respect it actually works like a set of elements from listA because this is usually what you want in such a setting. :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 . 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. Both of these variations are instance methods, which require an object of its class to be created before it can be used: public final Stream<T> sorted() {} This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License. The solution below is simple and should fix those issues: Location of index in list2 is tracked using cur_loclist. It would be helpful if you would provide an example of your expected input and output. 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. However, some may lead to under-performing solutions if not done properly. 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. Originally posted by David O'Meara: Then when you initialise your Comparator, pass in the list used for ordering. What is the shortest way of sorting X using values from Y to get the following output? Getting key with maximum value in dictionary? A Comparator can be passed to Collections.sort () or List.sort () method to allow control over the sort order. Why is "1000000000000000 in range(1000000000000001)" so fast in Python 3? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. In addition, the proposed solution won't work for the initial question as the lists X and Y contain different entries. 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(). my case was that I have list that user can sort by drag and drop, but some items might be filtered out, so we preserve hidden items position. Use MathJax to format equations. You can create a pandas Series, using the primary list as data and the other list as index, and then just sort by the index: This is helpful when needing to order a smaller list to values in larger. Create a new list and add first sublist to it. For bigger arrays / vectors, this solution with numpy is beneficial! Finally, we've used a custom Comparator and defined custom sorting logic. By default, the sort () method sorts a given list into ascending order (or natural order ). Thanks. 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.) It only takes a minute to sign up. 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. A stream represents a sequence of elements and supports different kind of operations that lead to the desired result. Sometimes, you might want to switch this up and sort in descending order. 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? 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. Something like this? It returns a stream sorted according to the natural order. 1. Sort Elements of a Linked List. How can I pair socks from a pile efficiently? To get a value from the HashMap, we use the key corresponding to that entry. Actually, List is an interface and most of the time we use one of its implementation like ArrayList or LinkedList etc. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 2. This is just an example, but it demonstrates an order that is defined by a list, and not the natural order of the datatype: Now, let's say that listA needs to be sorted according to this ordering. All the elements in the list must implement Comparable interface, otherwise IllegalArgumentException is thrown. Sometimes we have to sort a list in Java before processing its elements. How is an ETF fee calculated in a trade that ends in less than a year? From simple plot types to ridge plots, surface plots and spectrograms - understand your data and learn to draw conclusions from it. Making statements based on opinion; back them up with references or personal experience. 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. You can use this generic comparator to sort list based on the the other list. Excuse any terrible practices I used while writing this code, though. Once you have that, define your own comparison function which compares values based on the indexes of list Y. The most obvious solution to me is to use the key keyword arg. 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.