Questions tagged [linq]
Language INtegrated Query (LINQ) is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages.
604
questions
7
votes
2
answers
436
views
4
votes
1
answer
358
views
4
votes
2
answers
173
views
Finding which items have at least one common value with other items
I have the following collection :
...
- 421
1
vote
1
answer
162
views
ASP.NET MVC 5, EF 6 filter performance
I'm creating a filter with Linq in an ASP.NET MVC application. I was hoping I could get some tips on performance enhancements, aside from any possible performance enhancements.
I have a few questions:...
- 301
8
votes
3
answers
9k
views
LINQ Extension methods MinBy and MaxBy
LINQ Extension
I present a LINQ method ArgBy that returns the item of a sequence that corresponds to the predicate specified. Two additional methods ...
- 13.9k
4
votes
2
answers
804
views
Reverse Dictionary: Group from child array elements and get its minimum key
Objective
I have following array and would like to group by each child and get its smallest Id:-
...
- 225
4
votes
2
answers
483
views
DropDown tree with search
I fetch a bunch of categories for a DropDown tree, and have to implement search in this dropdown. If there is a match in one of the elements, it should also get all ...
- 153
5
votes
1
answer
311
views
Make utility using LINQ
Make() takes projects with a list of tuples representing project references in the form of (Dependency, Dependent) and returns ...
- 6,123
7
votes
4
answers
6k
views
LINQ for generating all possible permutations
Permutate() is supposed to generate all possible permutations of the source sequence:
...
- 6,123
3
votes
1
answer
158
views
LINQ for extracting N bottom items (async streams)
source.Bottom(n, x => x) should be the same as well known LINQ source.OrderBy(x => x).Take(n) but is more memory/run-time ...
- 6,123
9
votes
4
answers
4k
views
Filter search results by multiple filters in one operation
I want to filter search results by multiple filters at once. Is it possible to reduce the number of if statements?
My code:
...
1
vote
0
answers
1k
views
E-Commerce Mock App in Console
I have completed this E-Commerce Mock App in Console C# which I used object to store the data to apply some C# OOP and LINQ techniques. Since it is just a mock version, features are reduced to the ...
- 943
17
votes
3
answers
2k
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 ...
- 13.8k
5
votes
2
answers
139
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 ...
- 53
7
votes
5
answers
1k
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 ...
user73941
5
votes
3
answers
995
views
SkipLast of an IEnumerable<T> - Linq Extension
As my answer to this question, I came up with this solution:
...
user73941
2
votes
1
answer
160
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
1
answer
84
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)...
- 189
3
votes
1
answer
923
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 ...
- 131
3
votes
0
answers
41
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:
...
- 44.1k
2
votes
2
answers
51
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 ...
- 21
0
votes
2
answers
1k
views
Poker Hand evaluation
I want to evaluate Poker Hands an wrote the following Code:
https://dotnetfiddle.net/mxMvq9
Anything wrong / to imporve?
...
- 365
6
votes
5
answers
4k
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.
...
- 245
3
votes
2
answers
4k
views
2
votes
1
answer
260
views
Parse through an XDocument efficiently and match values to matching object
Minimum viable test program:
...
- 131
0
votes
1
answer
576
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 ...
- 119
4
votes
2
answers
311
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 ...
- 43
3
votes
1
answer
400
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 ...
- 233
1
vote
2
answers
5k
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 ...
- 227
-2
votes
1
answer
2k
views
Filtering List data using LINQ [closed]
In this code I have declared myPushData, myPushDataFilterd and myPushDataFilterd2 variables ...
- 107
12
votes
1
answer
5k
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 ...
- 24.1k
3
votes
5
answers
1k
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 ...
- 195
5
votes
2
answers
892
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 ...
- 409
1
vote
1
answer
3k
views
8
votes
4
answers
2k
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:
...
- 251
-2
votes
1
answer
1k
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 ...
- 11
-1
votes
1
answer
2k
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:
...
- 115
2
votes
3
answers
491
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 ...
3
votes
2
answers
5k
views
Get attribute values with LINQ to XML
I'm pulling the values from the following XML based on the attribute name.
...
- 165
4
votes
1
answer
173
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 ...
- 224
0
votes
1
answer
706
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:
...
- 53
5
votes
4
answers
821
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 ...
- 193
2
votes
1
answer
410
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 ...
- 412
5
votes
4
answers
986
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). ...
- 407
2
votes
0
answers
263
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
2
answers
265
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 ...
- 478
4
votes
1
answer
701
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
...
- 145
8
votes
3
answers
184
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 ...
- 263
5
votes
1
answer
116
views
Algorithm for tagging list of substrings from a list of strings
I have a list of utterances(strings)/corpus as the follows,
...
- 179
4
votes
3
answers
118
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 ...
- 143