Questions tagged [linq]
Language INtegrated Query (LINQ) is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages.
548
questions
0
votes
0answers
23 views
LINQ query to return LIST<T> subset of data
It's late and this works, but there has to be a better way to write this LINQ query, but I'm not smart enough. I can get it to work with a lambda expression, but I would prefer LINQ.
This is my json ...
9
votes
3answers
187 views
ExactlyOne extension method
I often find in codebases something on the order of if (sprockets.Count() > 0) which is easily replaced with LINQ's ...
5
votes
2answers
108 views
PLINQ code analysis in terms of efficiency of cryptographic hashes generation
I have the following code that I wrote in order to find the correct password by generating hashes out of all possible combinations and comparing each of them with the target. I'm trying to make ...
7
votes
5answers
512 views
Grouping into more groups in one iteration
I had a need to group the same dataset in several groups. So instead of repeatedly query the dataset, I made an extension that could do it once. The caveat is, that the result is materialized in ...
4
votes
3answers
182 views
SkipLast of an IEnumerable<T> - Linq Extension
As my answer to this question, I came up with this solution:
...
2
votes
1answer
115 views
Performance issue with empty lists
Here's my updated version of the problem I posted at Calculating time windows for entities, adding in suggested changes as well as a change I did so that the Reflection is 'cached' in a ...
2
votes
1answer
51 views
Populating dropdown lists, using SQL vs. using expression trees and reflection
I'm working with a large enterprise SQL Server database with dozens of tables that are used mainly as lookups to populate dropdown lists, etc. These tables all follow the convention of having (table)...
3
votes
1answer
77 views
Non brute force algorithm for Birthday Chocolate
Problem: https://www.hackerrank.com/challenges/the-birthday-bar/problem
Lily has a chocolate bar that she wants to share it with Ron for his birthday. Each of the squares has an integer on it. She ...
3
votes
0answers
23 views
Configure multiple application features by common criteria
My FeatureSerivce provides only basic APIs, so it is good in dealing with single features. Like I can configure only one feauture at a time:
...
2
votes
2answers
38 views
LINQ queries to generate a report on accrued work time on projects
The following code fetches data from a MySql database to generate a simple report on accrued work time on projects.
I've been away from Entity Framework for a while and looking at this code you can ...
0
votes
2answers
87 views
Poker Hand evaluation
I want to evaluate Poker Hands an wrote the following Code:
https://dotnetfiddle.net/mxMvq9
Anything wrong / to imporve?
...
5
votes
4answers
172 views
Take N elements from List of Lists
I've come with a solution super tricky for a simple requirement. I think I could solve the problem using LinQ, but I'm not seeing it so clearly at all.
What's sure, I'm not comfortable with my code.
...
3
votes
2answers
168 views
2
votes
1answer
67 views
Parse through an XDocument efficiently and match values to matching object
Minimum viable test program:
...
0
votes
1answer
63 views
LINQ or Lambda for two foreach query [closed]
I have a Document Name Table in my SQL database and Files in the Content folder.
I have two lists: ListOfFileNamesSavedInTheDB and ...
4
votes
2answers
120 views
Making a list of customers who buy the top N items from a supplier
I have a method that works perfectly well and does what it's supposed to, albeit a little slow (30 - 40 seconds). I would like to be able to speed it up or at least make it more efficient, any ideas ...
3
votes
1answer
153 views
Logging inside a Linq fluent chain [closed]
I've posted this to Stack Overflow, but someone voted to close as they felt it was opinion based, so I'm bringing it over to Code Review.
I have some Linq fluent chains to shape an original ...
1
vote
2answers
143 views
Using IQueryable.GroupBy to count related database entities
Given a DbSet<Client> from an Entity Framework 6 DbContext, I need to count the number of related ...
-2
votes
1answer
482 views
Filtering List data using LINQ [closed]
In this code I have declared myPushData, myPushDataFilterd and myPushDataFilterd2 variables ...
11
votes
1answer
499 views
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 ...
3
votes
5answers
581 views
Finding Isogram Word
An isogram (also known as a "nonpattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.
The ...
5
votes
2answers
863 views
Going from IQueryable<IEnumerable<myObj>> to IEnumerable<myObj>
I have a "GetPersonsPerDepartment()" method returning a IQueryable<IEnumerable<Person>> while I'm trying to get a simple ...
0
votes
1answer
360 views
6
votes
3answers
753 views
Custom implementation of the linq Zip operator for different length lists
Based on my answer I have my implementation of linq Zip operator which operates on different length lists, and loops shortest list.
My implementation:
...
-2
votes
1answer
135 views
Method to populate a dictionary from properties
I have a class with some properties. In the class I have a method that is "collecting" all the properties in a specific instance of the class to a dictionary, with the properties name being the ...
-2
votes
1answer
519 views
Reuse Select Expression in LINQ
I have three methods to get the user details based on attributes:
Find user details by id,
Find user details by username,
Find user details by email
Here is the program class:
...
2
votes
3answers
131 views
Grouping report data by one of two criteria
I have a report with a group by filter. A stored procedure returns all the data and maps it to IEnumerable<EventListRow>. The code should then group the data ...
2
votes
2answers
855 views
Get attribute values with LINQ to XML
I'm pulling the values from the following XML based on the attribute name.
...
3
votes
1answer
71 views
Determining if there is data left after fetching a page of data
I just faced a problem where I needed to know if extra data was present in a given collection after a Take operation took place. Specifically, this is related to ...
0
votes
1answer
150 views
Sorting table using multiple columns [closed]
I want to sort entries in a given list on Entry column in most efficient way. Here is how my entries look:
...
5
votes
4answers
770 views
Take a desired string, iterate through objects to see if it exists in a given field and append a number until a unique string is found
I wanted to in the most generic way possible write a method in C# to achieve the following.
Take in a string, a set of objects, and a function to access the field of a given object
Look at all of the ...
2
votes
1answer
116 views
Handling related generic type parameters
In answering a question on StackOverflow, it occurred to me that a more generic version of GroupBy for C# that delegated membership in each group to a class could ...
4
votes
4answers
156 views
Add dash between more than two consecutive numbers and comma between other numbers in array
I have an ordered array of integer values: 10, 11, 12, 13, 15, 16, 19
and I need to write a dash between first and last consecutive values when there are more than two consecutive values (10-13). ...
2
votes
0answers
173 views
Handler for jQuery DataTable search with filters and pagination
This AjaxCompound is invoked every time when the user types a key for search or click to sort. It contains 1million data 10 distinct rows by compound name. It takes 1.1 minutes and return only 1-5 KB ...
4
votes
2answers
148 views
EnumerableHelpers: a partial implementation of LINQ for .NET Framework 2.0
Here is a static class with some helper methods for some common LINQ operations on enumerables, built against .NET Framework 2.0. This class is part of the xofz.Core98 library.
Edit: a full review ...
4
votes
1answer
247 views
Find a list of Windows Services by given criteria
My goal is to implement a method, which finds a list of Windows Services that match given set of criteria:
SearchString: A search string
...
8
votes
3answers
159 views
Build clusters from connections (virus propagation)
The scenario is the following: There is a list of persons and places where those persons visit. Each person is connected to a single or multiple places. See the picture below, where O[i] represents ...
5
votes
1answer
92 views
Algorithm for tagging list of substrings from a list of strings
I have a list of utterances(strings)/corpus as the follows,
...
4
votes
3answers
107 views
List mapping of large data set from file
I have a list of items 116 thousand and my mapping function is taking quite some time to process. I am using the file helpers library to write the CSV to disk but its the for each that is taking ...
0
votes
1answer
625 views
adding properties together from list of objects using LINQ
Looking to see if there is a simpler way to achieve this. I would love if I could keep the return as a one-line LINQ expression. I want to grab the total number of ...
2
votes
0answers
38 views
Correct Way to Retrieve Header Records With Filtered Detail Records [closed]
I wrote this in LinqPad. It works. The whole point was to retrieve header records, and only include some detail records. I'm looking for possible improvements to this, specifically around the ...
2
votes
2answers
1k views
Linq IEnumerable extensions for void functions
I found myself wanting to use Linq to map void methods to an IEnumerable to modify all items. The existing Linq methods require a return variable when mapping, since they are based on ...
2
votes
0answers
98 views
Implementing the IQueryable counterpart method of the IEnumerable method?
I have created this method to simulate SQL's IN operator:
...
5
votes
3answers
2k views
LINQ method that selects an item based on previous one
my requirement is to implement a way to filter a collection of elements based on a value of previous one.
For example to only select a number that is larger than the previous one. I don't currently ...
5
votes
2answers
192 views
Porting functional programming code to Linq
I am very new to C# programming, so for practice I thought I would try to port a simple haskell function over to Linq. From learn you a haskell, there is the following implementation of powerset:
<...
5
votes
1answer
81 views
Representing relations between devices when presented with only one-to-many mappings
There are devices that communicate between each other.
Already existing in the Legacy codebase is a list of one-to-many mappings between the devices. I have written a function in my backend that ...
0
votes
1answer
57 views
Data validation for to check required fields are mapped
Can I break the below foreach and IF statements into LINQ expression. Also, performance wise which will be better. Please suggest.
...
1
vote
0answers
43 views
Querying a database to find notifications to comments
I have a solution what I think is not the best, and I want to make this not so expensive.
I'm using MVC 5 + SignalR (hubs) + EF + UnitOfWork + Generic Repos.
I have a table ...
6
votes
1answer
63 views
Return true from enumerable that calls function unless that function ever returns false
Is there a tighter way to write this code?
...
0
votes
1answer
682 views
Entity Framework MVC updating db using a repository method [closed]
I have inherited this code from a legacy project, and it is throwing a
New transaction is not allowed because there are other threads running in the session.
error.
Now I know the problem here is ...
