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: I need to store the rank because the price may change Double StartTime, Double EndTime, Double Value and string Id. However, those are all lamda expression style. Why did US v. Assange skip the court of appeal? Learn more about Stack Overflow the company, and our products. Is "I didn't think it was serious" usually a good defence against "duty to rescue"? I think using Join then looping through the list would be more efficient. I've tried using ForEach and various forms of select, etc.. nothing seems to work right. If x.Value has decimals, I want to change that value to take just the first decimal woithout rounding it. Should I re-do this cinched PEX connection? Was Aristarchus the first to propose heliocentrism? What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? Use .ToList () in order to convert query in list that you can work with. Find centralized, trusted content and collaborate around the technologies you use most. Can you perhaps include some description of your answer instead of just posting a blob of code? Simple deform modifier is deforming my object. I mean, if PopulateChanges() is returning you a List<> of DateTime arrays, and you are going through all of them and setting them to DateTime.MinValue, what exactly is the code unit that you want to put in the delegate? 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. What does 'They're at four. Remember that linq is a querying language, which means all you can do is query it. Is there any known 80-bit collision attack? See below for arguments against it. Why are players required to record the moves in World Championship Classical games? 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? 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. The OP since updated the question and having it makes no more sense at all since it's true 100% of the time. You can't modify a collection while you're iterating it. var list = from something in someList select GetModifiedObject (x); // but change one property private MyType true : false, Searches for the specified object and returns the index of the first occurrence within the list, Note that it returns -1 if the value doesn't occur in the list, This will help you in getting the first or default value in your LINQ List search. rev2023.5.1.43405. You can create a extension method: public static IEnumerable Do(this IEnumerable self, Action action) { Certainly, the nested for loop works, and I can certainly place it in a function (which I have already done). It's not them. Weighted sum of two random variables ranked by first order stochastic dominance. Use LINQ to get items in one List<>, that are not in another List<>. I would externalize that part into a function to make it more manageable. Where can I find a clear diagram of the SPECK algorithm? Why refined oil is cheaper than cold press oil? Connect and share knowledge within a single location that is structured and easy to search. my code gives error can you please tell how i do this. I think your code is perfectly readable and won't improve much if you force it to have lots of lambdas and such. Be aware that it only updates the first company it found with company id 1. //d What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Can you use lambda expressions and .find? What differentiates living as mere roommates from living in a marriage-like relationship? I need to store the rank because the price may change afterward. If you simply need to get the elements that are of a certain type, you can do this: That would give the subset that are MyQuota or are directly assignable to that type. 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. To use a linq statement to get a new List of CorrectionQuota you would do something like this: Transform the results into what you want first and then make the new List. How are engines numbered on Starship and Super Heavy? With LINQ2SQL you query the database and then modify the returned objects. MathJax reference. I have a list where i whant to change the value of a double property in that list if that property has decimals. You can create a extension method: public static IEnumerable Do(this IEnumerable self, Action action) { What were the most popular text editors for MS-DOS in the 1980s? At the moment I am doing it like this: You could do it using the let keyword. Is there any known 80-bit collision attack? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. Most of these methods (First, Single, Any, ) cannot be. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. "Signpost" puzzle from Tatham's collection, Simple deform modifier is deforming my object. 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. How do I get the number of elements in a list (length of a list) in Python? The code looks like this: For the life of me, I can't seem to figure this one out. To learn more, see our tips on writing great answers. Connect and share knowledge within a single location that is structured and easy to search. 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. I don't think this would help. All I am doing is creating a working example, as my FYI says.. i'm really caling just the for loop part of it (the rest is just setup) in an area that's different from this. You should iterate your list, and modify your values like: foreach (var student in myList) { if (student.Name == "Tom") { student.Marks = 35; } } Or foreach (var student This will give syntax error, How to set a value in one list when comparing it with other list using LINQ, How a top-ranked engineering school reimagined CS curriculum (Ep. What is Wario dropping at the end of Super Mario Land 2 and why? 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. { 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. This assumes that there are only 3 types of name. UPDATE This can be simplified to be listOf For multiple. I think you try to add a complete list instead of a single CheckItems instance. Should I re-do this cinched PEX connection? If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? 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. Passing negative parameters to a wolframscript. How are engines numbered on Starship and Super Heavy? How do they work? 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? "Signpost" puzzle from Tatham's collection. rev2023.5.1.43405. I suspect that this can be written shorter using LINQ over objects syntax. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? Here I have a simple example to find an item in a list of strings. 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. Is a downhill scooter lighter than a downhill MTB with same performance? ex. How do I remedy "The breakpoint will not currently be hit. 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. The i.age = 10 part is not different from the item.age = 10 part. Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? I just want something more concise that can be used more easily in a delegate without creating a multi-line monster. Asking for help, clarification, or responding to other answers. Why are players required to record the moves in World Championship Classical games? If you want the index of the element, this will do it: You can't get rid of the lambda in the first pass. Be aware that it only updates the first company it found with company id 1. Connect and share knowledge within a single location that is structured and easy to search. If you had a more generic collection IEnumerable, you can use Select in Linq to build a projection where property will be set as desired (original collection will be left untouched!): listOfRequestAssigned .Where (x => x.RequestedNumber == CurrentRequest) .Select (x => { x.RequestCompleted = true; return x; }) 1. ', referring to the nuclear power plant in Ignalina, mean? warning? Find centralized, trusted content and collaborate around the technologies you use most. There's no -1 index (not found) in my example. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. In my application I have a list of items I need to sort by price and set a rank/position index for each item. Identify blue/translucent jelly-like animal on beach. If you want to modify all returned objects, you still have to use a loop to iterate over the objects. The ToList is making a list, populating it, and the immediately discarding it. WebIf you really want to use linq, you can do something like this li= (from tl in li select new Myclass { name = tl.name, age = (tl.name == "di" ? Making statements based on opinion; back them up with references or personal experience. 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. If we had a video livestream of a clock being sent to Mars, what would we see? Has the Melford Hall manuscript poem "Whoso terms love a fire" been attributed to any poetDonne, Roe, or other? Asking for help, clarification, or responding to other answers. I use a simple list here. Making statements based on opinion; back them up with references or personal experience. Are there any canonical examples of the Prime Directive being broken that aren't shown on screen? Reme. It was designed to bring native data querying to .NET. Embedded hyperlinks in a thesis or research paper. What is this brick with a round back and a stud on the side used for? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. To learn more, see our tips on writing great answers. 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. If it really is a List you don't need LINQ, just use: If you are looking for the item itself, try: bool insertOrderNew = lOrders.Find(r => r == "1234") == null ? For Starship, using B9 and later, how will separation work if the Hydrualic Power Units are no longer needed for the TVC System? WebYou can try LINQ. I like this. Which was the first Sci-Fi story to predict obnoxious "robo calls"? AddRange takes an enumerable, and it will enumerate it all on its own. In my application I have a list of items I need to sort by price and set a rank/position index for each item. In both cases , the update is not done with Linq :). I want to do: Just change all values for a property in all elements of my collection. int index = mylist.FindIndex (p => p.id == 1); if (index<0) { mylist.Add (car3); } else { mylist [index] = car3; } This just uses the existing FindIndex to An interesting question, but Linq is about querying and what you're doing here doesn't look much like a query to me. A new List, yes - but containing the same items, which will be updated correctly. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How a top-ranked engineering school reimagined CS curriculum (Ep. If I understand you correctly you have to enumerate your nested array for several different reasons and would like to encapsulate that functionality to be reused.. Why is it shorter than a normal address? What should I follow, if two altimeters show different altitudes? Parabolic, suborbital and ballistic trajectories all follow elliptic paths. Connect and share knowledge within a single location that is structured and easy to search. Not the answer you're looking for? Adding EV Charger (100A) in secondary panel (100A) fed off main (200A), Folder's list view has different sized fonts in different folders. Asking for help, clarification, or responding to other answers. Single will return a single result, but will throw an exception if it finds none or more than one (which may or may not be what you want): Note that SingleOrDefault() will behave the same, except it will return null for reference types, or the default value for value types, instead of throwing an exception. Using LINQ to change values in collection, How a top-ranked engineering school reimagined CS curriculum (Ep. 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. As sircodesalot mentioned, you can't use linq to do something like that. Find centralized, trusted content and collaborate around the technologies you use most. correctionQoutas is a custom object that has four properties. I don't really see how this is any different. 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. // 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. Avoiding it would require enumerating the collection: Again, I wouldn't recommend this. 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? (from c in listOfCompany where c.id == 1 select c).First ().Name = "Whatever Name"; For Multiple updates. Close enough for me, I think. Folder's list view has different sized fonts in different folders. No symbols have been loaded for this document." Why did DOS-based Windows require HIMEM.SYS to boot? Since you save your result to a new List anyway, you can just Select the result instead: Oh and % wont do you any good here anyway, your number would be converted to int first, if it works at all. When to use .First and when to use .FirstOrDefault with LINQ? is there such a thing as "right to be heard"? Find centralized, trusted content and collaborate around the technologies you use most. Identify blue/translucent jelly-like animal on beach. There are certainly ways to (ab)use LINQ to achieve the same results, but I'd consider them to be dirty hacks. What differentiates living as mere roommates from living in a marriage-like relationship? For Starship, using B9 and later, how will separation work if the Hydrualic Power Units are no longer needed for the TVC System? Making statements based on opinion; back them up with references or personal experience. C# void QueryHighScores(int exam, int score) { var highScores = from student in students where student.ExamScores [exam] > score select new { Name Use MathJax to format equations. LINQ stands for Language Integrated Query. Which language's style guidelines should be used when writing code that is supposed to be called from another language? Connect and share knowledge within a single location that is structured and easy to search. Not the answer you're looking for? The below is practically the same as the answer provided by Florian Schmidinger: Thanks for contributing an answer to Stack Overflow! Or use (list ?? FYI, I know that DateTime defaults to MinValue, in reality this is clearing the arrays to default after they've already been set. rev2023.5.1.43405. First, there's no real need to use. It should not be hard to analyze the complexity of this. The list may be a class with several properties and some are used for search. Do you want the item in the list or the actual item itself (would assume the item itself). Adding EV Charger (100A) in secondary panel (100A) fed off main (200A). I have attached my sample program. 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( Would My Planets Blue Sun Kill Earth-Life? I'm trying this but can't get it right: What is the symbol (which looks similar to an equals sign) called? LINQ is about querying, not for updating collections. Any suggestion? 20 : 30)) By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Normally I use a for loop or anonymous delegate to do it like this: LINQ is new for me. The following example depicts the behavior of the Enumerable.Distinctmethod on a This should work Of course you can write your own ForEach extension for IEnumerable but I remember I had side-effect with it. Since you want to change the properties of the elements in your enumeration, you should not be using linq or List.ForEach for that. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, how to add more than one result to the list using a linq query, Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. The below is practically the same as the answer provided by Florian Schmidinger: Thanks for contributing an answer to Stack Overflow! When to use .First and when to use .FirstOrDefault with LINQ? Your code is O(n m), where n is the length of a and m is the length of b. When do you use in the accusative case? You can use Magiq, a batch operation framework for LINQ. I assume you want to change values inside a query so you could write a function for it 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 There are many such queries used in Linq, such as projecting transofrmation, etc.. Making statements based on opinion; back them up with references or personal experience. Thanks. According to this link: Update all objects in a collection using LINQ, you can do this: repo.getAll().Select(c => {c.B = value; return c;}).ToList(); However, Thanks for contributing an answer to Stack Overflow! 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. You have also a way to set a default value. Do I need to check if list is null first? When changes are cleared, I need to reset the times to MinValue. This new list is then discarded. When do you use in the accusative case? How to call asynchronous method from synchronous method in C#? One other point I should mention is that the Select method does a projection of some specific information to return to an IEnumerable. "Signpost" puzzle from Tatham's collection. Did the drapes in old theatres actually say "ASBESTOS" on them? Also, Linq is only used here to loop over the collection, just like wudzik's answer. Asking for help, clarification, or responding to other answers. 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. Not the answer you're looking for? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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: That being said, ToList() has some disadvantages - mainly, it's doing a lot of extra work (to create a List) that's not needed, which adds a large cost. 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. It can be done this way as well foreach (Company company in listofCompany.Where(d => d.Id = 1)).ToList()) //using linq list = Students.Where (s => s.Name == "ABC").ToList (); //traditional way foreach (var student in Students) { if (student.Name == "ABC") list.Add In general Linq is a query- not an update tool, but you can use a foreach: var currentRequests = Web3. How do I make a flat list out of a list of lists? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Using LINQ to remove elements from a List, How to use LINQ to select object with minimum or maximum property value. How do I split a list into equally-sized chunks? To learn more, see our tips on writing great answers. rev2023.5.1.43405. LINQ is not really intended to be used for updating collections. 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? If you want to avoid this anonymous type here is the To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? I disagree, it is in fact a query, but a query with side effects. Has the cause of a rocket failure ever been mis-identified, such that another launch failed due to the same problem? Thanks for contributing an answer to Stack Overflow! How would you do a "not in" query with LINQ? What is the Efficiency and Performance of LINQ and Lambda Expression in .Net? //d Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Update all objects in a collection using LINQ, Concat all strings inside a List using LINQ, How to use LINQ to select object with minimum or maximum property value, Searching if value exists in a list of objects using Linq, All possible array initialization syntaxes, String.IsNullOrWhiteSpace in LINQ Expression. It's about querying, i.e. Eric Lippert wrote a great blog post about the subject that is worth a read: "foreach" vs "ForEach". One thing to note about using SingleOrDefault is that because it throws an exception if more than one match is in the list, it has to iterate through every item, where FirstOrDefault will stop searching once the first match is found. I don't have a C# compiler here but maybe AddRange instead of Add works: Thanks for contributing an answer to Stack Overflow! Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Can my creature spell be countered if I cast a split second spell after it? EDIT: What were the most popular text editors for MS-DOS in the 1980s? So simply iterate over that enumeration and set the new values: Note that I cut the trailing decimals by simple arithmetic instead of converting the values to strings and back. x.Value = Convert.ToDouble(string.Format("{0:0.0}", x)) : x.Value = x.Value); This gives you an 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Note that you can add a ForEach extension method which performs an action on each object, but I would still recommend avoiding that. It only takes a minute to sign up. Why did US v. Assange skip the court of appeal? Ok, this should hopefully be of some help: I would also look into PLINQ as you have a lot of data to plow through. Two MacBook Pro with same model number (A1286) but different year. For Starship, using B9 and later, how will separation work if the Hydrualic Power Units are no longer needed for the TVC System? Doing changes must be done in other logic. from c in listOfCompany where c.id == 1 select c => Connect and share knowledge within a single location that is structured and easy to search. Why is it shorter than a normal address? Connect and share knowledge within a single location that is structured and easy to search. This search will find the first or default value, which it will return. Generating points along line with specifying the origin of point generation in QGIS. Great answer. how to check for a value in a list of decimal C#, C# Select From Json List Using Where Clause, String search function XML file with ASP.NET MVC. When new changes occure, then those elements get a new DateTime. Which method performs better: .Any() vs .Count() > 0? Simply put: what you're doing is, it will create new list which will replace old one, BTW the only LINQ here is. Does a password policy with a restriction of repeated characters increase security? If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? using Linq would be: listOfCompany.Where(c=> c.id == 1).FirstOrDefault().Name = "Whatever Name"; rev2023.5.1.43405. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. ), Ubuntu won't accept my choice of password. He also rips off an arm to use as a sword. rev2023.5.1.43405. Adding EV Charger (100A) in secondary panel (100A) fed off main (200A). Which reverse polarity protection is better and why? Here is an example. 1. To learn more, see our tips on writing great answers. If we had a video livestream of a clock being sent to Mars, what would we see? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. var newList = correctionQoutas.Select(x => x.Value%1 != 0 ? Extracting arguments from a list of function calls. What were the most popular text editors for MS-DOS in the 1980s? When do you use in the accusative case? Why waste the time on it. Boolean algebra of the lattice of subspaces of a vector space? Nevermind, actually you can get rid of the lambdas for a few cases Great answers! create enumerables over existing collections. LINQ Approach (Likely Unnecessary) If you absolutely had to use LINQ, you could use a Select () call to map each of your existing elements to updated versions : // What is Wario dropping at the end of Super Mario Land 2 and why? Without digging into what your actual conversion function is doing. I'm querying to return every element of a List, so I can then set those values. Was Aristarchus the first to propose heliocentrism? It's not LINQ, and it's not really much different to your nested for loops, just slightly less verbose. But,in my case, I must repeat the foreach in many collections, and I didn't want to repeat the loop.
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