A lambda is an expression that acts as an anonymous function. Use this tag if you would like to discuss the appropriateness of a lambda or anonymous function in your code.
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Java Stream - Collections - remove duplicates based on string and presence/absence of local date value
I have a list of objects with a string (name) and a local date (date of deletion).
I wish to implement uniqueness on these objects based on:
If two objects have the same name, then I wish the one ...
3
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1answer
31 views
Memory allocation tracking using anonymous lambda wrapper
I had this idea to exploit anonymous lambdas that are immediately executed that wrap around an allocation function to track those allocations in a statically created Stats object.
This is the code I ...
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0answers
25 views
Producer Consumer With Multiple Dependents
I put together a ProducerConsumer class that wraps the C#'s BlockingCollection class with some bells and whistles (producers can have multiple consumers, consumers can have lambdas, built in parallel ...
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1answer
53 views
Church Numerals
Here is exercise 2.6 from SICP:
Exercise 2.6: In case representing pairs as procedures wasn’t
mind-boggling enough, consider that, in a language that can manipulate
procedures, we can get by ...
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1answer
42 views
Lambda to obtain a new merged object
The requirement is to iterate over a list of Foos, and when 2 Foos have the same id merge ...
4
votes
1answer
48 views
Credit card / IMEI check digit in Kotlin
I recently had the need to implement Luhn's Algorithm in a Java/Kotlin application. I needed a function that would add the check digit to the string of a number like a credit card or IMEI. It could be ...
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35 views
Finding vowels, digits, whitespaces and consonants
i am creating a simple app to find vowels, digits, whitespaces and consonants. the basic idea is to practice multi-threading and writing readable code.
So here is the code:
...
6
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1answer
43 views
Count how many times a value is referenced in a grid
I've got list of points: List<Point> seedPoints. Each Point contains x and ...
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1answer
41 views
What is the best way to extract method?
The code snippet is what I want to do. Previously I use a different version of my code. But it is out of joint according to Python coding guidelines because I was assigned my lambda function to a ...
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2answers
119 views
Validating input values in C#
I began studying C# 5.0 a few days ago and am trying to avoid duplicated code for validation of input values.
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2answers
282 views
Calculate GS1 / SSCC / UPC check digit
I try to write a function which calculates the check digit for shipping label based on the algorithm provided by GS1
http://www.gs1.org/how-calculate-check-digit-manually
Version 1: my first try
<...
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vote
2answers
22 views
advfind() template
This code basically allows you to provide a collection and a lambda and have the lambda operate on each value iterated even allowing modification of the data if you wish.
I would like to be able to ...
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1answer
467 views
Python Pandas Apply with a Lambda Function
I have a table in pandas that has two columns, QuarterHourDimID and StartDateDimID ; these columns give me an ID for each date / ...
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votes
2answers
73 views
Custom key class for .NET 3.5 framework
I use .NET 3.5 framework, so no tuples. I have many use cases where I have to create a custom key for a dictionary. How can I make this better?
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2answers
105 views
Most efficient dict filter on key tuple?
I have a dict wherein a value needs to be retrievable by any one of several keys. It seemed that making multiple dictionaries or multiple entries in a single ...
2
votes
1answer
87 views
Return most recent DateTime C# Entity Framework
Job -> Many Quotes
Quote -> EmailLogList
EmailLogList -> Many EmailLogs
I want to return a CreatedDate from an EmailLog which has been created most ...
4
votes
1answer
196 views
(C++14) Handling state in C-style function pointer callbacks
I'm having some issues coming up with a sensible solution for using shared state in a C-style function pointer. I am using GLFW to handle my OpenGL context and have created a thin wrapper around all ...
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2answers
530 views
Custom sorting of dates
I have implemented a class which implements a list of my custom DateObj. I have sorted the list in a peculiar manner based on the current month. I achieved my ...
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1answer
62 views
Updating all members of a struct in database
This function is part of our company's project code.
The following function updates six members of struct CpGSMTimeDelayQuery -- ...
2
votes
1answer
67 views
Writing strings to the screen over time
The following methods just write strings to the screen over time to make it look like a typing effect, instead of all at once. The only difference is the argument in the ...
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1answer
93 views
JavaFX await implementation
I'm debating trying to take a crack at getting something similar to C#'s async-co-routine like nature over on JavaFX.
This is technically feasible since the Quantem toolkit exposes the ...
4
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1answer
54 views
Write Once Use Everywhere: Multidimensional array traversal
I have a structure that is organized much like a Sudoku board, where individual cells reside in an n x n region, and those regions reside in an n x n area. I need to be able to address both the ...
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vote
2answers
167 views
Read a txt file and split into 2 csvs based on regex
So I have been told that my code is not good and needs refactoring. I'm struggling to see what I need to do. How do I specify the success and failure conditions for lambda? Also don't get what the ...
1
vote
1answer
39 views
Use an optionally passed-in block without repeating yourself
I need to open and read several files for a project. Some of them are plain text files, and I just want a standard File.open to read from. One of them is an XML ...
3
votes
4answers
1k views
Checking whether a list is sorted, ascending or descending
What is the best way to conditionally use an operator? All 3 methods seemed acceptable to me, and the last 2 better.
If you're curious: I've got a list which is unsorted, and many other lists which ...
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vote
1answer
269 views
Lambda to collect properties in a child object
I have a class:
public class ProductInvoice {
//Some other properties.
private List<ProductEntry> productEntries = newArrayList();
//otherMethods
}
...
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3answers
346 views
Filtering units by a dynamic Lambda expression
I have a simple if statement which, based on user input, determines which expression is going to be utilized. It looks like it can be done better.
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1answer
238 views
Routing Java objects using conditional consumers
As per a previous question here and answers I got, I used it to get a new implementation. I found that I have to make two implementations match once "to ignore other consumers after matching once" and ...
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1answer
211 views
Mandelbrot Streams
A recent Mandelbrot question (Hi @EBrown) in C# inspired me to build my own using the Java 8 parallel streams to implement the parallelism that's useful for computing each pixel value.
The intention ...
4
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2answers
135 views
Function for timing executions (inspired by MATLAB tic toc)
Inspired by MATLAB's tic/toc I've written a short helper function for calculating execution time.
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2answers
1k views
Return lambda expression based on parameters
This function returns a lambda expression based on the parameters sent. I am sure there is a better way to do this.
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3answers
483 views
Duplicate words in a text
Here is a simplified implementation to obtain the duplicate words in a text using lambda expressions.
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1answer
1k views
Event-listener implementation
While writing a C++ GUI application more or less from scratch I needed some form of an event-listener system, preferably using lambdas. An event should be able to have multiple listeners and the user ...
2
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1answer
116 views
Sort files by the type of file
I need to sort files by the type of the File. To accomplish the task I first wrote the code below:
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6answers
3k views
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1answer
261 views
Catch all checked exceptions and turn into unchecked exception
I am currently trying to learn Lambdas and following the book Java SE8 for the really Impatient and just finished Chapter 1 of it. This is the question, I am trying to get done with:
Didn’t you ...
7
votes
1answer
227 views
Proper checked exception handling with lambda functions
I'm having trouble finding a clean way to handle checked exceptions thrown by a lambda function passed as a parameter in Java.
I'm writing a Client which will interact via RMI with a Server to play a ...
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1answer
65 views
Repetitive code for a projected field in a lambda
I have a simple projection in my code. Taking away the majority of the fields which are not of interest, it looks like the following:
...
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votes
2answers
5k views
Optimize method to iterate to over Map<String, List<Object>>
I have a Map<String, List<Object>> multiFieldMap and I need to iterate over its value set and add the value to ...
5
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1answer
158 views
Multiple functions to establish a fallback value for a property until not null
I have a property (called "Head") that can be set externally. When "Head" is not set, it uses Unity3D's MonoBehaviour functions to try to find the best value for "...
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2answers
519 views
Printing removed items using lambdas and streams
I'm struggling to make my lambdas readable.
I've seen various approaches. Below are three different examples that all do the same thing.
Forgive the example: I suspect there are better actual ...
2
votes
2answers
158 views
Comparing triangles using Java 8 streams
I'm trying to get more familiar with Java 8 streams as they seem to be very powerful (and shorter), so I rewrote a method to use streams. However I'm not very satisfied with it and would like some ...
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1answer
1k views
Asynchronous connect() with one function call, using C++11 lambdas and Boost.Asio
I've wanted to write a C++11 class for making IPv4 TCP connections and figured that it probably could be done with just one static function using some shared_ptr and lambda "magic". The following code ...
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votes
2answers
515 views
Simple calculator implemented with lambdas
I was searching for a way to exercise the Java 8 concepts I've been learning, especially pertaining to Lambdas. Incidentally, I hadn't used any swing in a while and wanted a refresher. This is the ...
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3answers
890 views
The Beauty and the Strings
This originally appeared in Facebook's hacker cup 2013. Solving it was fun, though I find myself looping through similar data quite often.
Challenge:
Print the maximum beauty of strings.
...
4
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1answer
2k views
Java 8 CompletableFuture - fan out implementation
I was wondering what is the best way to implement a fan out type of functionality with Java 8 Completable future. I recently rewrote a function that had a bunch of old ...
7
votes
4answers
35k views
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 ...
8
votes
3answers
291 views
Sending duplicate to heaven with Java 8
Follow up to Duplicate like a weapon, arrays like heaven.
@rolfl suggested in chat that I try to complete this challenge again in a Java 8 friendly way. I took the opportunity to also employ the ...
7
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2answers
2k views
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1answer
96 views
Effective use of branch prediction in terrain generator
I am trying to learn how branch optimization works.
For an experiment, I have a recursive fractal terrain generation and I have moved all if statements to binary ...
