565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Close enough for me, I think. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. For the sake of the example, T in this case is an object similar to the following: Is there a way I can make this more efficient? Connect and share knowledge within a single location that is structured and easy to search.
I want to do: Just change all values for a property in all elements of my collection. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. You really shouldn't use LINQ to perform side effects. Note that you can add a ForEach
extension method which performs an action on each object, but I would still recommend avoiding that. To learn more, see our tips on writing great answers. What is Wario dropping at the end of Super Mario Land 2 and why? This solves the problem by resorting to nullable ints: If you want to count the number of items that match: And don't forget to check the list for null in any of these cases. Do you want the item in the list or the actual item itself (would assume the item itself). Canadian of Polish descent travel to Poland with Canadian passport. You can't modify a collection while you're iterating it. Ubuntu won't accept my choice of password. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, This question is difficult/dangerous to answer without misleading people into thinking that LINQ is an appropriate solution to your problem. Find centralized, trusted content and collaborate around the technologies you use most. It's also a violation of the expectations involved with LINQ - LINQ is about querying, which suggests there shouldn't be side effects when using LINQ, and the entire purpose here is to create side effects. Thanks. Not the answer you're looking for? Folder's list view has different sized fonts in different folders. Not knowing the full extent of the data types behind the MatchA, MatchB and ToUpdate properties, it'll be difficult to give an answer which completely solves your performance issues. How to set a value in one list when comparing it with other list How do I clone a list so that it doesn't change unexpectedly after assignment? Is a downhill scooter lighter than a downhill MTB with same performance? Can I use LINQ to find an item in the list? Making statements based on opinion; back them up with references or personal experience. Why don't we use the 7805 for car phone chargers? I don't really see how this is any different. How can I control PNP and NPN transistors together from one pin? If you want to avoid this anonymous type here is the Can my creature spell be countered if I cast a split second spell after it? Find centralized, trusted content and collaborate around the technologies you use most. There are several different ways to accomplish but here is one using linq and one with out this would allow you to reuse this and do different things to each item. Since you haven't given any indication to what you want, here is a link to 101 LINQ samples that use all the different LINQ methods: 101 LINQ Samples. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Not the answer you're looking for? 1. Why did DOS-based Windows require HIMEM.SYS to boot? c# - conditional Updating a list using LINQ - Stack Overflow To learn more, see our tips on writing great answers. What is the best way to give a C# auto-property an initial value? See below for arguments against it. dont forget the return syntax it took me one hour, Very neat! Where will return all items which match your criteria, so you may get an IEnumerable with one element: First will return the first item which matches your criteria: Note that FirstOrDefault() will behave the same, except it will return null for reference types, or the default value for value types, instead of throwing an exception. Why refined oil is cheaper than cold press oil? ', referring to the nuclear power plant in Ignalina, mean? c# - ToList method in Linq - Stack Overflow Sorry, guys. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. rev2023.5.1.43405. Why? When to use .First and when to use .FirstOrDefault with LINQ? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You can create a extension method: public static IEnumerable Do(this IEnumerable self, Action action) { The only difference between them is that the .First method will throw an exception if there is no such object in the collection when the second one returns the To subscribe to this RSS feed, copy and paste this URL into your RSS reader. LINQ: Select an object and change some properties without Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Hm, using your example and stuffing various random data into the objects into the two lists of the sizes you specify, it executes in less than 1/100 second on my machine. Be aware that it only updates the first company it found with company id 1. For multiple (from c in listOfCompany where c.id == 1 select c).First( Can you perhaps include some description of your answer instead of just posting a blob of code? Can my creature spell be countered if I cast a split second spell after it? Why are players required to record the moves in World Championship Classical games? Connect and share knowledge within a single location that is structured and easy to search. Reme. 8 Answers. Find centralized, trusted content and collaborate around the technologies you use most. This search will find the first or default value, which it will return. Why did US v. Assange skip the court of appeal? I have a bit of code that i'd like to turn into a linq expression (preferably with lambdas) to make it easier to use as a delegate. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, There is no ForEach for IEnumerable. It can be done this way as well foreach (Company company in listofCompany.Where(d => d.Id = 1)).ToList()) WebYou can try LINQ. Making statements based on opinion; back them up with references or personal experience. Google "LINQ side effects" for more information. Has the Melford Hall manuscript poem "Whoso terms love a fire" been attributed to any poetDonne, Roe, or other? Not the answer you're looking for? What should I follow, if two altimeters show different altitudes? Asking for help, clarification, or responding to other answers. I have attached my sample program. You could make it O(n + m) (assuming only a small number of items from a match each item in b) by using a hash table. The below is practically the same as the answer provided by Florian Schmidinger: Thanks for contributing an answer to Stack Overflow! Where can I find a clear diagram of the SPECK algorithm? Asking for help, clarification, or responding to other answers. It only takes a minute to sign up. How would you do a "not in" query with LINQ? But,in my case, I must repeat the foreach in many collections, and I didn't want to repeat the loop. What were the most popular text editors for MS-DOS in the 1980s? I need to store the rank because the price may change If you want to create a new List with each element set to a value, you can do this: If you really want to do it using ForEach/LINQ, it's possible to abuse Select (but I don't recommend it): Can you describe some use cases of how you propose to use the said delegate? Using LINQ to change values in collection, How a top-ranked engineering school reimagined CS curriculum (Ep. Does a password policy with a restriction of repeated characters increase security? Set operations (C#) | Microsoft Learn Your code is O(n m), where n is the length of a and m is the length of b. If you make your expression return a value, and add something that will fully evaluate the query, such as ToList (), to the end, then it will "work", ie: Connect and share knowledge within a single location that is structured and easy to search. I really don't understand why you say it's not meant for this. To learn more, see our tips on writing great answers. Why refined oil is cheaper than cold press oil? Since you want to change the properties of the elements in your enumeration, you should not be using linq or List.ForEach for that. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What's the cheapest way to buy out a sibling's share of our parents house if I have no cash and want to pay less than the appraised value? Making statements based on opinion; back them up with references or personal experience. I suspect that this can be written shorter using LINQ over objects syntax. The check if you have decimal places is unneccessary too, since the output will be a double anyway. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? Should I re-do this cinched PEX connection? Are there any canonical examples of the Prime Directive being broken that aren't shown on screen? If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, How to overcome foreach loop for list object dynamically. foreach(var item in self) { Making statements based on opinion; back them up with references or personal experience. What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? rev2023.5.1.43405. I used to use a Dictionary which is some sort of an indexed list which will give me exactly what I want when I want it. I like this. What is the symbol (which looks similar to an equals sign) called? I didn't know either Single() or SingleOrDefault(). Does a password policy with a restriction of repeated characters increase security? I want to compare these lists using LINQ and if IDs from both lists are equal, I want to set WorkingID in the first list, A list. An interesting question, but Linq is about querying and what you're doing here doesn't look much like a query to me. It was designed to bring native data querying to .NET. If you need to transform the elements, then you need to use the Select() LinQ function: This gives you an IEnumerable, to freeze the contents and actually do the evaluation, you can use the ToList() function after the Select() function. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? var newList = correctionQoutas.Select(x => x.Value%1 != 0 ? If we had a video livestream of a clock being sent to Mars, what would we see? If you want to create a new List with each element set to a value, you can do this: var changes = Enumerable.Range (0, width) .Select (x => Use method syntax. The OP since updated the question and having it makes no more sense at all since it's true 100% of the time. What differentiates living as mere roommates from living in a marriage-like relationship? 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI, Moving List View items from one list to another, Best way of updating a list of unique items, Find items in a table that match a set of conditions in another table, Multiple similar manager classes for handling scroll lists, Recursive search on Node Tree with Linq and Queue, Collecting data into objects and POSTing to 3rd Party API, Python scripts that generate valid ngrams for use in pseudoword generation. c# - Add items to list from linq var - Stack Overflow By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. The i.age = 10 part is not different from the item.age = 10 part. I have another List that contains the data, this just maps each element of the string array to a time when they last changed. Should I re-do this cinched PEX connection? Why waste the time on it. Asking for help, clarification, or responding to other answers. How do I make a flat list out of a list of lists? c# - Set values with a Linq-Query? - Stack Overflow Do I need to check if list is null first? To learn more, see our tips on writing great answers. this would be used for thing done to each date time as opposed to thing done with each date time That would be slightly different. How to force Unity Editor/TestRunner to run at full speed when in background? Asking for help, clarification, or responding to other answers. This assumes that there are only 3 types of name. I just want to get a taste of LINQ searching from enumeration case. How do I remedy "The breakpoint will not currently be hit. rev2023.5.1.43405. I would externalize that part into a function to make it more manageable. //d C# Set field of all items in list to same value - Stack Overflow The list may be a class with several properties and some are used for search. Here is one way to rewrite your method to use LINQ: public static int GetItemIndex(string search) { List _list = new List() { "one", "two", Making statements based on opinion; back them up with references or personal experience. Be aware that it only updates the first company it found with company id 1. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. and MatchingColumnName1 and MatchingColumnName2 are properties of collections. If we need to find an element from the list, then we can use the Find and FindAll extensions method, but there is a slight difference between them. Update all objects in a collection using LINQ, LINQ's Distinct() on a particular property, Deserializing JSON to .NET object using Newtonsoft (or LINQ to JSON maybe? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. c# - assign value using linq - Stack Overflow When do you use in the accusative case? I found SingleOrDefault to be my answer of choice - same as Single but returns 'null' if it can't find it. Following the logic of the first example, we could use, msdn.microsoft.com/en-us/library/bb342451(v=vs.110).aspx, How a top-ranked engineering school reimagined CS curriculum (Ep. When to use .First and when to use .FirstOrDefault with LINQ? There's not a single query in LINQ that modifies the queried collection (hence "query"). 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. I don't have a C# compiler here but maybe AddRange instead of Add works: Thanks for contributing an answer to Stack Overflow! He also rips off an arm to use as a sword, Identify blue/translucent jelly-like animal on beach, Ubuntu won't accept my choice of password. If it is possible, how? // Next, when I try to add vnlist to vendlist, I get an error as I cannot add this to the list I get and error saying I have some invalid arguments. Whenever I wish to access my margins values, for instance, I address my dictionary: So, depending on what you're doing, a dictionary can be useful. (Your question does not sound like you want to copy the original objects). You're trading one assignment for one condition, that shouldn't change much. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, That's great. When to use .First and when to use .FirstOrDefault with LINQ? Can you use lambda expressions and .find? Nevermind, actually you can get rid of the lambdas for a few cases Great answers! It's an easy way to filter out nulls. Parabolic, suborbital and ballistic trajectories all follow elliptic paths. using Linq would be: listOfCompany.Where(c=> c.id == 1).FirstOrDefault().Name = "Whatever Name"; Here is one way to rewrite your method to use LINQ: You can use FirstOfDefault with the Where LINQ extension to get a MessageAction class from the IEnumerable. 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 the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? and do I need to check if _list is null in the form of from .. in _list? What were the most popular text editors for MS-DOS in the 1980s? Why are players required to record the moves in World Championship Classical games? For multiple. To learn more, see our tips on writing great answers. If you need to add any IEnumerable collection of elements to the list you need to use AddRange. Why don't we use the 7805 for car phone chargers? To learn more, see our tips on writing great answers. rev2023.5.1.43405. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Extract values from HttpContext.User.Claims, Ultrawingrid - Select row based on unique value, Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. I think you try to add a complete list instead of a single CheckItems instance. I just want something more concise that can be used more easily in a delegate without creating a multi-line monster. "Signpost" puzzle from Tatham's collection, Simple deform modifier is deforming my object. Asking for help, clarification, or responding to other answers. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? Is there any known 80-bit collision attack? There are certainly ways to (ab)use LINQ to achieve the same results, but I'd consider them to be dirty hacks. If you want to modify all returned objects, you still have to use a loop to iterate over the objects. What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Also, you Where does the version of Hamapil that is different from the Gemara come from? LINQ stands for Language Integrated Query. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How do I stop the Flickering on Mode 13h? I've tried using ForEach and various forms of select, etc.. nothing seems to work right. First, there's no real need to use. What were the most popular text editors for MS-DOS in the 1980s? Which method performs better: .Any() vs .Count() > 0? Code Review Stack Exchange is a question and answer site for peer programmer code reviews. Web3. Two MacBook Pro with same model number (A1286) but different year. This appears to be a response to another answer rather than an answer to the question. To learn more, see our tips on writing great answers. Generic Doubly-Linked-Lists C implementation, "Signpost" puzzle from Tatham's collection, Embedded hyperlinks in a thesis or research paper. Weighted sum of two random variables ranked by first order stochastic dominance. Also, Linq is only used here to loop over the collection, just like wudzik's answer. Identify blue/translucent jelly-like animal on beach. Making statements based on opinion; back them up with references or personal experience. What differentiates living as mere roommates from living in a marriage-like relationship? Besides, the LINQ equivalent probably wouldn't be any less verbose than my example above. c# - assign value using linq - Stack Overflow UPDATE This can be simplified to be listOf { When to use .First and when to use .FirstOrDefault with LINQ? Or use (list ?? Linq expression to set all values of an array to a given value Find centralized, trusted content and collaborate around the technologies you use most. Assigning a value to a parameter of an lambda does not change the queried collection Linq expression to set all values of an array to a given value, How a top-ranked engineering school reimagined CS curriculum (Ep. Which language's style guidelines should be used when writing code that is supposed to be called from another language? In both cases , the update is not done with Linq :). 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. Not the answer you're looking for? A boy can regenerate, so demons eat him for years. Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. You can select multiple fields using linq Select as shown above in various examples this will return as an Anonymous Type. WebThis is the best I have right now: var allCountries = repository.GetCountries (); var topitem = allCountries.Single (x => x.id == 592); var finalList = new List (); finalList.Add rev2023.5.1.43405. Most of these methods (First, Single, Any, ) cannot be. It's not them. What are the advantages of running a power tool on 240 V vs 120 V? Is a downhill scooter lighter than a downhill MTB with same performance? That's all it does. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? But then, at this point, you're better off (with less typing) doing it the "clear" way: This is shorter, very clear in its intent, and very clean. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Would My Planets Blue Sun Kill Earth-Life? Normally I use a for loop or anonymous delegate to do it like this: LINQ is new for me. This should work Of course you can write your own ForEach extension for IEnumerable but I remember I had side-effect with it. "Signpost" puzzle from Tatham's collection. It's better to operate on List. 10 : (tl.name == "marks" ? What's the cheapest way to buy out a sibling's share of our parents house if I have no cash and want to pay less than the appraised value? I'm using VS 2008. What should I follow, if two altimeters show different altitudes? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. It doesn't work because Select() doesn't actually iterate through the collection until you enumerate it's results, and it requires an expression that evaluates to a value. User without create permission can create a custom object from Managed package using Custom Rest API. I disagree, it is in fact a query, but a query with side effects. It's not LINQ, and it's not really much different to your nested for loops, just slightly less verbose. Use MathJax to format equations. What's the cheapest way to buy out a sibling's share of our parents house if I have no cash and want to pay less than the appraised value? Adding EV Charger (100A) in secondary panel (100A) fed off main (200A). What is this brick with a round back and a stud on the side used for? Connect and share knowledge within a single location that is structured and easy to search. Why did US v. Assange skip the court of appeal? Was Aristarchus the first to propose heliocentrism? rev2023.5.1.43405. To learn more, see our tips on writing great answers. Why did US v. Assange skip the court of appeal? Find centralized, trusted content and collaborate around the technologies you use most. To learn more, see our tips on writing great answers. LINQ is about querying, not for updating collections. I'm not happy yet. What you could do, if you don't want to do it the first way and if your collection is a list already (but not an IEnumerable) you can use the ForEach extension method in linq to do what you're asking. It wouldn't be at all difficult to write a LINQ "query" with side-effects to do what Mystere Man requires, but (a) it would be a dirty hack, and (b) it would probably require as much code as an equivalent, cleaner, non-LINQ solution. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA.