Questions tagged [linq]
Language INtegrated Query (LINQ) is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages.
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SudokuSharp Solver with advanced features
Even though it's the first time I'm writing something this "big", it feels like I know C# quite well (it is very similar to Java after all). It's been nice to learn LINQ also and I am very impressed ...
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Converting DataTable to List of class
I am using ExcelDataReader to import an Excel file to a dataset.
Example Excel table:
...
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40
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2
answers
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Wait, is this... LINQ?
Context
I'm working on a little project that consists in a series of Microsoft Excel add-ins (.xlam). The code being submitted for review here, is located in the ...
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Multiple indexes over an in memory collection for faster search
I have a big in-memory collection of following simplified class:
...
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7
answers
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Are these if-statements too fancy?
I just rewrote this:
if (budgetRemaining != 0 || totalOpenInvoices != 0)
{
}
Like this:
...
- 1,212
28
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8
answers
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LINQ approach to flatten Dictionary to string
I have a Dictionary<string,string> and want to flatten it out with this pattern:
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4
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Filtering a list of vertices that lie inside a cylinder, with and without LINQ
Since I don't know how LINQ works under the hood, I can't decide what version is best to use in term of rapidity of execution. I've done some testing with my testing data (Point Cloud) but I can't see ...
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Single line FizzBuzz solution in LINQ
Now FizzBuzz itself isn't a big challenge but I agree that it can be a good tool to see if someone can code or not. I wanted to practice my LINQ a little bit so here's my single line FizzBuzz ...
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Linq me a FizzBuzz
I got this requirement recently:
Write some code that prints out the following for a contiguous range of numbers:
the number 'fizz' for numbers that are multiples of 3
'buzz' for numbers that are ...
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votes
1
answer
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LINQ to SQL Joining Entities
I have two tables, one for jobs, and one for the names of industries (e.g. automotive, IT, etc).
In SQL I would just do:
...
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19
votes
6
answers
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Increment up the build number in AssemblyInfo.cs on every build
I just wrote this short little program to increment up the build number for my projects every time I build them.
After compiling this exe, I just call it in the pre-build command line.
I did take ...
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Optimizing List<string> performance
I have a List<string> being stored in my cache with about 600K members. I want this to act as the backend for an Ajax autocomplete box. It's accessible ...
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Using C# properties for simple operations, where should I draw the line?
Should I be putting Linq statements inside of an objects properties? Is that a best practice or is that a no no? Also if that is ok, where do I draw the line with this? I assume db access is ...
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Solving Fizz Buzz using LINQ in C#
The Fizz Buzz challenge is well-known and should not need any explanations, right?
I recently got a bit bored and came up with a solution for Fizz Buzz using LINQ and even asynchronous code and a lot ...
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3
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ExactlyOne extension method
I often find in codebases something on the order of if (sprockets.Count() > 0) which is easily replaced with LINQ's ...
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Generic Calculator and Generic Number
.NET does not support generic numbers. It is not possible to enforce a generic method with generic argument T that T is a number. The following code will simply not compile:
...
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Imposing a sort order on a query
I've always been told "never use goto, there's always a better way" and for the longest time I just accepted it. Lately though, I've been running into such scenarios in which I have to repeat this bit ...
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LINQ query that filters elements from a list of object
I have two lists of objects Person and PersonResult. Both are linked through the property ...
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How can I refactor to avoid repetition finding the index of strings in a list?
I have a list of strings where I want to find the index of a first- and second-choice video compressor.
Logic: If the first choice is available, return its index. If not, and the second choice is ...
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What do you think of this improvement of Linq's GroupBy method?
Linq already has a set of GroupBy methods for enumerable, which returns IEnumerable<IGrouping<TKey, TSource>>. I dislike this return type because it ...
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Counting the number of points that have both a larger theta and a larger radius than a given point
I don't like the fact that I am selecting all the points, even though I only care about the count of them.
Which of the from parts should appear first, if it even ...
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answer
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Filtering a collection by an async result
I'm trying to do something like this:
var loudDogs = dogs.Where(async d => await d.IsYappyAsync);
The "IsYappyAsync" property would return a ...
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1
answer
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Update first and last item in List<T>
I am trying to do the following. I have a list of Custom objects:
...
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12
votes
1
answer
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Find the odd occurrences in an array
Recently, I came across this problem on Codility. I am aware there is a bit of similarity to this question and this question, but I am trying to achieve this in C#.
The problem is as follows:
A ...
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4
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Calculating totals of a transaction
I am working on a project where I have to calculate the totals of a transaction. Unfortunately, coupons have proven to be quite an issue. There are four types of coupons: transaction percentage, ...
user1139
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2
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Given an array A[] and a number x, check for pair in A[] with sum as x
LINQ/FP style:
Assert.IsTrue(new[] {1,2,3}.AnyPairSum(4));
Where:
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12
votes
4
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Generate sequence in Linq
I want to generate a sequence using Linq that goes from 10 to 100 with a step size of 10. The sequence also must contain a custom value (in the correct order).
This is what I have now, and I'm ...
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2
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CSV reader using StreamReader and LINQ
Mostly due to readability, I am using the following code to
find a specific csv file on a drive
read that CSV file using a streamReader
parse it into a ...
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votes
2
answers
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Query Builder pattern with use of FluentApi
Recently, I've come up with an idea of building a custom query builder combine with FluentApi.
Expected usage:
...
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votes
1
answer
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Linq for ObservableCollection
Purpose
ObservableCollection<T> is not strictly a WPF class, but its intended purpose seems to be for use in WPF. It's the standard implementation of ...
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4
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Country code lookup for each line in a CSV file
I'm trying to write a program that has a for loop, inside of which I have lambda expression to get a certain value. The loop has about 20,000 iterations. Including ...
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PermMissingElem- find the missing element in a given permutation in C#
I just encountered this question in codility but apparently this question has been asked in java already (here, here).
Task description
A zero-indexed array A consisting of \$N\$ different integers ...
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Using LINQ or Lambda instead of nested and multiple foreach statements
I want to use a better syntax than nested foreach statements to overwrite the initial list with items from the second list.
In the code below:
I want to overwrite ...
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FizzBuzz in accordance with standards
I wrote FizzBuzz. My aim is to use C# Code Standards correctly, and write flexible code. How can I improve my solution according to code standards? How can it be better in general?
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String join of distinct string
I have a class like this one:
class EmailClass
{
public string MailAdresse { get; set; }
public string MailAdresseCC { get; set; }
}
Through a JSON ...
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answers
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Give me thy name, I'll invoke thee
This generic function invokes a property of a given object by name:
...
user42412
11
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2
answers
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IdentifierReferenceResolver: resolving at project level
One of the most important parts at the core of rubberduck is the IdentifierReferenceResolver class, which is responsible for resolving each declaration as the parse ...
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Poker Hand Evaluator, take 2
This is following up on my previous attempt, which was admittedly done fast and not-so-well. This code attempts to allow comparing two poker hands to determine a winner, not only evaluating a given ...
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1
answer
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C++ linq-like library
I want to implement something like C# Linq in C++
Currently only select and where is implemented, but others should be fairly ...
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Too Many Staff Meetings
I recently got in really deep on a question to find the overlapping meetings and I rewrote a bit of the code and added some things to the code, and I would just like a general review of my code and ...
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Split IEnumerable by predicate
In order to divide an IEnumerable in C# by a predicate, I implemented the following (in a static class):
...
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3
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Refactor foreach statement to LINQ
I have been working on a project and I'm actually refactoring some code. I have encountered myself with lots of foreach and if statements, which could be easily replace with LINQ.
But I have this ...
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Get result from UI thread to non-UI thread when using await Task.Run
I have an application where I use Task to run an operation. During the operation, there can be a problem which will need some user interaction (continue or not). I ...
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1
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Using Linq instead of multiple foreach loops
A project I'm working on often has lists within lists within lists etc. The original author often uses complicated linq expressions, but when adapting them I mostly get hopelessly bogged down and ...
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3
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Read/write to XML using LINQ
This will compile, but I'm thinking that this implementation of read/write is very hard coded and would not be easily adapted to larger situations where large XML documents are being processed or if ...
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Left join query of user profiles
I have the following left join LINQ query that is returning the results that I expect, but it does not "feel" right. I need ALL records from the UserProfile table.
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Tracking Entity Changes (not EF)
So, I kept refactoring my Sage300 API wrapper - I wanted the client code to feel just like using Entity Framework - this is the closest I got to it:
...
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Filter out nulls from sequence of nullables to produce sequence of non-nullables
While introducing nullable reference types to our enterprise application's codebase, I found that we are often using LINQ on sequences of nullable reference types where we filter out the nulls using <...
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