Even if there is a solution out there, I'm not sure I'd use Linq for something like this. 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. Can I use the spell Immovable Object to create a castle which floats above the clouds? Asking for help, clarification, or responding to other answers. Does a password policy with a restriction of repeated characters increase security? 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. But,in my case, I must repeat the foreach in many collections, and I didn't want to repeat the loop. "Signpost" puzzle from Tatham's collection, Simple deform modifier is deforming my object. AddRange takes an enumerable, and it will enumerate it all on its own. I don't have a C# compiler here but maybe AddRange instead of Add works: Making statements based on opinion; back them up with references or personal experience. 1. There's not a single query in LINQ that modifies the queried collection (hence "query"). What is Wario dropping at the end of Super Mario Land 2 and why? Close enough for me, I think. What are the advantages of running a power tool on 240 V vs 120 V? 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. The ToList is making a list, populating it, and the immediately discarding it. Be aware that it only updates the first company it found with company id 1. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. There are many such queries used in Linq, such as projecting transofrmation, etc.. To learn more, see our tips on writing great answers. The i.age = 10 part is not different from the item.age = 10 part. Asking for help, clarification, or responding to other answers. Reme. Not the answer you're looking for? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Asking for help, clarification, or responding to other answers. 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. it will be discarded but, how will you replace older list values? Connect and share knowledge within a single location that is structured and easy to search. Identify blue/translucent jelly-like animal on beach. 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( Could a subterranean river or aquifer generate enough continuous momentum to power a waterwheel for the purpose of producing electricity? To learn more, see our tips on writing great answers. from c in listOfCompany where c.id == 1 select c => How can I control PNP and NPN transistors together from one pin? If it is possible, how? Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey, Sometimes when modifying properties in a foreach loop, the changes do not remain. To learn more, see our tips on writing great answers. One possible way to do this is to use ToLookup(): Another way to do basically the same thing would be using join: Also, you should really use better variable names. One other point I should mention is that the Select method does a projection of some specific information to return to an IEnumerable. Think about a typical Linq2SQL query where you query data and then update the values. 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 => To learn more, see our tips on writing great answers. I'm trying this but can't get it right: Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Thanks for contributing an answer to Stack Overflow! Certainly, foreach is the right way. Find centralized, trusted content and collaborate around the technologies you use most. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Do I need to check if list is null first? How do I make a flat list out of a list of lists? You can't modify a collection while you're iterating it. Most of these methods (First, Single, Any, ) cannot be. Two points. When to use .First and when to use .FirstOrDefault with LINQ? Adding EV Charger (100A) in secondary panel (100A) fed off main (200A). 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. If you want to avoid this anonymous type here is the Use LINQ to get items in one List<>, that are not in another List<>, Simple deform modifier is deforming my object. Weighted sum of two random variables ranked by first order stochastic dominance. I think you try to add a complete list instead of a single CheckItems instance. var newList = correctionQoutas.Select(x => x.Value%1 != 0 ? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. You could try something like this (not a pure LINQ approach): Here is one way, assuming a class structure as follows: You can join the second list on matching IDs: I think using Join then looping through the list would be more efficient. Now, the only reason I added count was so that once 10000 items in a have been updated, the loop will stop, otherwise it will take a very long time to go thru all of the items. Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. Eric Lippert wrote a great blog post about the subject that is worth a read: "foreach" vs "ForEach". Learn more about Stack Overflow the company, and our products. I don't really see how this is any different. 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. When to use .First and when to use .FirstOrDefault with LINQ? The property value is not changed. You really shouldn't use LINQ to perform side effects. 20 : 30)) Find centralized, trusted content and collaborate around the technologies you use most. Doing changes must be done in other logic. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. So, if you wanted to grab only a specific property from a collection you would use that. 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. Any suggestion? Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? I have attached my sample program. Connect and share knowledge within a single location that is structured and easy to search. Thanks for contributing an answer to Stack Overflow! If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. However, those are all lamda expression style. rev2023.5.1.43405. 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. How a top-ranked engineering school reimagined CS curriculum (Ep. Double StartTime, Double EndTime, Double Value and string Id. Do you want the item in the list or the actual item itself (would assume the item itself). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. First, there's no real need to use. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. See below for arguments against it. How to force Unity Editor/TestRunner to run at full speed when in background? Ubuntu won't accept my choice of password. 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. Asking for help, clarification, or responding to other answers. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, That's great. rev2023.5.1.43405. What were the most popular text editors for MS-DOS in the 1980s? Simple deform modifier is deforming my object. Why did DOS-based Windows require HIMEM.SYS to boot? Find centralized, trusted content and collaborate around the technologies you use most. 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 will, except for one small detail the numbering will start from 2. And the enumerable containing the objects isn't modified at all. When do you use in the accusative case? To learn more, see our tips on writing great answers. The code will look something like this. 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; }) You can create a extension method: public static IEnumerable Do(this IEnumerable self, Action action) { What is the difference between Python's list methods append and extend? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. It's not them. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? What is the symbol (which looks similar to an equals sign) called? The below is practically the same as the answer provided by Florian Schmidinger: Thanks for contributing an answer to Stack Overflow! It can be done this way as well foreach (Company company in listofCompany.Where(d => d.Id = 1)).ToList()) 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. 8 Answers. What is Wario dropping at the end of Super Mario Land 2 and why? Using LINQ to change values in collection, How a top-ranked engineering school reimagined CS curriculum (Ep. Find centralized, trusted content and collaborate around the technologies you use most. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. You have also a way to set a default value. var list = from something in someList select GetModifiedObject (x); // but change one property private MyType To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Your first example is actually the correct method. How is this any different? rev2023.5.1.43405. Why don't we use the 7805 for car phone chargers? 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. To learn more, see our tips on writing great answers. At the moment I am doing it like this: You could do it using the let keyword. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? create enumerables over existing collections. Two MacBook Pro with same model number (A1286) but different year. To learn more, see our tips on writing great answers. Why did US v. Assange skip the court of appeal? Set list property value using LINQ ForEach. Generating points along line with specifying the origin of point generation in QGIS. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. What were the most popular text editors for MS-DOS in the 1980s? So any LINQ way to search like "from .. in where select", Nah, sorry. What were the most popular text editors for MS-DOS in the 1980s? Was Aristarchus the first to propose heliocentrism? (from c in listOfCompany where c.id == 1 select c).First ().Name = "Whatever Name"; For Multiple updates. It's exactly what I was looking for, How a top-ranked engineering school reimagined CS curriculum (Ep. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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? Concat all strings inside a List using LINQ, Using LINQ to remove elements from a List. Use a combination of query syntax and method and MatchingColumnName1 and MatchingColumnName2 are properties of collections. If we had a video livestream of a clock being sent to Mars, what would we see? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Identify blue/translucent jelly-like animal on beach. 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 WebYou can try LINQ. rev2023.5.1.43405. I need to store the rank because the price may change What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Here is an example. I am using below linq query to set value of SecKey, but I still see the old value in list studentData, below id the sample I am 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. > var boys = new List {"Harry", "Ron", "Neville"}; > boys.IndexOf ("Neville") 2 > boys [2] == "Neville" True This will help you in getting the first or default value in your LINQ List search This search will find the first or default value, which it will return. Identify blue/translucent jelly-like animal on beach. Why is it shorter than a normal address? I think using Join then looping through the list would be more efficient. This article shows the three ways in which you can write a LINQ query in C#: Use query syntax. Use method syntax. Use a combination of query syntax and method syntax. The following examples demonstrate some simple LINQ queries by using each approach listed previously. 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. What are the advantages of running a power tool on 240 V vs 120 V? This new list is then discarded. What are the advantages of running a power tool on 240 V vs 120 V? Why are players required to record the moves in World Championship Classical games? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Not the answer you're looking for? One more way to check the existence of an element in a List: You want to search an object in object list. Certainly, the nested for loop works, and I can certainly place it in a function (which I have already done). 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? foreach(var item in self) { Why refined oil is cheaper than cold press oil? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Making statements based on opinion; back them up with references or personal experience. A boy can regenerate, so demons eat him for years. Not the answer you're looking for? What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? Not the answer you're looking for? Thanks for contributing an answer to Stack Overflow! Can these methods be used with other collections too like, @yellavon these are extension methods on any type that implements. What positional accuracy (ie, arc seconds) is necessary to view Saturn, Uranus, beyond? 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 Your code is O ( n m ), where n is the length of a and m is the length of b. Embedded hyperlinks in a thesis or research paper. Has the Melford Hall manuscript poem "Whoso terms love a fire" been attributed to any poetDonne, Roe, or other? It was designed to bring native data querying to .NET. Besides, the LINQ equivalent probably wouldn't be any less verbose than my example above. Why did US v. Assange skip the court of appeal? I think you try to add a complete list instead of a single CheckItems instance. 10 : (tl.name == "marks" ? 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. 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 Find centralized, trusted content and collaborate around the technologies you use most. The following example depicts the behavior of the Enumerable.Distinctmethod on a I use a simple list here. Why did US v. Assange skip the court of appeal? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Not the answer you're looking for? Ok, this should hopefully be of some help: I would also look into PLINQ as you have a lot of data to plow through. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The check if you have decimal places is unneccessary too, since the output will be a double anyway. LINQ is not really intended to be used for updating collections. Which reverse polarity protection is better and why? Why are players required to record the moves in World Championship Classical games? Asking for help, clarification, or responding to other answers. 1. using Linq would be: listOfCompany.Where(c=> c.id == 1).FirstOrDefault().Name = "Whatever Name"; 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. If the null hypothesis is never really true, is there a point to using a statistical test without a priori power analysis? 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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( Thanks for contributing an answer to Stack Overflow! Why waste the time on it. What differentiates living as mere roommates from living in a marriage-like relationship? IEnumerable vs List - What to Use? List1 and List2 are two collections.
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