Questions tagged [collections]
Collections APIs provide developers with a set of classes and interfaces that makes it easier to handle collections of objects.
328
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Grouping and summing by condition from three mongodb collections
I have three mongodb collections. I would like to group the collections by date, month and year, then sum by condition in order to display totals from the three collections in one table. However, i ...
3
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2
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135
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C macro based dynamic array library
This library is a fork of eteran/c-vector. It is macro based, so that it is generic, without void pointers and additional functions. This of course means that it has the downsides of macros in C. The ...
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2
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112
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Sort a dict by keys, assuming keys are orderable
I found a suspicious code snipped in an existing project in which I am involved as a developer. The code sorts a dict by its keys, so that if iterated over the dict,...
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1
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184
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Yet another sparse set implementation
I got inspired by this blog post and implemented a fixed-size sparse set, removing the need for vectors, because the sparse set's size equals at least ...
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2
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A not so simple C++20 circular queue
This container reduces the number of memory allocations on queue-type operations (push + pop) compared to std::deque. Basic performance tests indicates a performance similar to std::deque where main ...
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Simple C++ circular queue
I wrote a simple C++20 circular queue.
https://github.com/torrentg/cqueue
Here is cqueue.hpp
...
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1
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39
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Iterating over JSON more effectively
Problem:
I need to get data from JSON file containing information about "contributors". Each contributor has an atrribute jobs, which is a list of string-...
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1
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105
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Class that wraps a collection and tracks if its elements were visited
The VisitedCollection is a collection wrapper for setting and tracking if elements were visited (removed in terms of the wrapper)
I have concerns regarding:
should ...
- 254
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3
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97
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How to efficiently build an object from list or array of strings
I am working with an API that delivers some data in a QStringList or basically a list of strings. The data contains keys and values but it is not a ...
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2
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284
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Implemented Sorting of Map by Value and then by Key in java
So I had this requirement to get the frequency of names appearing in a list
and then print the one appearing the most number of times. If there is a clash, print the one which comes first in the ...
0
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1
answer
282
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std::list implementation learning exercise
I want to improve my algorithms and data structures in C++ understanding and also learn how the standard library containers are implemented. I implemented a std::vector in a previous review and this ...
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Faster way to find items from one list in another one [closed]
I would like to check if a string appears in a list of strings. For that, I have chosen the List<string> type, as follows:
...
- 301
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C smart string implementation using preprocessor
I have wrote a smart string container implementation for use in my application, but as I'am not such professional C programmer I have doubts about is I'am did it right and is there ways how to improve ...
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2
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184
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std::vector implementation learning exercise
I want to improve my algorithms and data structures in C++ understanding and also learn how the standard library containers are implemented. This resizing_array is based on the std::vector.
My ...
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Spring Boot Integration Test with SQS and Elastic Search
I have the following integration test that starts with sending message to sqs queue and ends with checking elastic search if the associated object added to db.
The part of application I want to test ...
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-1
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1
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66
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Most efficient way to track a collection of targets in range of a source object [closed]
In my game there are space ships and each of these space ships tracks which other ships are in range of it. I need to perform certain logic when a target ship comes in range of another ship, and ...
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1
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101
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Action on each element of an inline list
I'm trying to learn the "functional" part of C#/.Net for work, and I'm not sure if this is a good way to write this statement.
I was also trying to reduce duplicated code while not ...
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C Typed Vector that implements type-safety, encapsulation and lazy initialization
C Typed Vector
I wasn't happy with the various dynamic array / vector implementations in C, so I made my own. In general, I'm not the biggest fan of C-preprocessor madness, but alas for this ...
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191
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Implementation of Dynamic Array with allocators and C++20
To train my skills in C++, I decided to implement the well-known "Dynamic array" data structure on my own. I realized early on that using pointers or smart pointers is wrong, as it leads to ...
- 131
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2
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291
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Prime numbers iterator
I am not familiar with iterators. I am confused with the traits approach and the traditional one. I don't know which one I should use in 2021.
I wrote a minimal ...
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1
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234
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Custom implementation to provide an immutable range of a container without copying it
I needed to pass a const reference to part of a std::vector without copy. I posted the previous version in my earlier question, thank you for the great support! As ...
- 405
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2
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101
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Is there a way to simplify getting the character that appears the most in a collection with Linq?
I have a collection of strings, all of which are three characters in length:
...
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1
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767
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Python script to automate the creation of Linux LXC containers
Like the title suggests, I wrote a script in Python that uses the python3-lxc library to automate the creation of Linux LXC containers. I realised that containers ...
- 101
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1
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294
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A multi key/value type "folded" map class template
I have recently come across a use case where I need to lump many maps into a single container. These maps can have different combinations of key/value types, but they all differ from one another.
For ...
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1
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66
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R Container for Multiple data.frame with a Brief Description of the Content of the data.frame
For a project I have a large dataset with a multitude of variables from different questionnaires. Not all variables are required for all analyses.
So I created a preprocessing script, in which subsets ...
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Hash table implemented in C with open addressing
While posting this, I noticed there are quite a few similar C hash table implementations here already. So I figured one more wouldn't hurt. :-) In any case, I'm writing a teaching article on "how ...
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340
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Take element of a Set collection depending on the value of another element
I had to populate the fields of a Service object using a Set (HashSet) with any configuration parameters -> ...
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1
answer
41
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An exercise concering Kotlin Set
Task description:
Declare a function twoInThree(a: Set, b: Set, c: Set), which returns the set of all elements, which are contained in exactly two of the three given sets a, b, c.
My solution:
...
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4
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1
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101
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Data set with many variables in Python, many indented dictionaries?
I am working with a data set that has many variables. Currently I am storing the data in many indented dictionaries in the following way:
...
- 143
2
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1
answer
672
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Generic hashmap with dynamic resizing and collision handling
This is a (more or less) continuation of a previous post I made: Generic implementation of a hashtable with double-linked list.
I got lots of valuable feedback, so I decided to rewrite the entire ...
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1
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453
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C++20 "FixedArray" Container (dynamically allocated fixed-size array)
I've wrote a FixedArray to fit seamlessly (function-wise) with the default C++ containers, including working with algorithms/etc. It is a dynamically allocated, but fixed size array.
Code
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1
answer
77
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Print the App Name Using Latest Version
I am trying to solve a problem, where we are given an app name, service name, and version number of an api. We need to print the name of app, which is using the latest version for most of the service.
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2
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1
answer
888
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Generic Doubly Linked-list implementation in C++
I am just learning about C++ templates and generic types, I decided it would be nice to try to create a generic container class as a challenge and test my knowledge in the process. Here is what I have ...
user228914
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125
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Using Method Chaining To Alter Last Item Added To Collection
There is a Name class with properties that represent different components that make up a person's name. A Name object requires a FirstName and ...
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2k
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Java group list of maps by value and insert as grouped list
Not sure if I am overcomplicating the requirement but this is what I need (for simplicity I will show a the List<Map<String, Object>> as a ...
user9492428
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1
answer
96
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Dictionary or custom Collection
I have a list of rule names coming from .xml file. These rule names needs to be validated against rule names in database (Validator.cs). If valid, then ...
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Implementation of Doubly Linked List with sentinel in C++ trying to replicate the stl std::list [closed]
I am currently trying to replicate the STL std::list interface with my own list implementation (doubly linked list with sentinel) to learn about all the advanced ...
1
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2
answers
72
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Class template, custom container
So I wrote this class template for a custom container. Basically, it stores elements and their occurences. When an element is pushed into the container, if it ...
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4
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816
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Reviewing custom array List class of java
I am using JDK 12 and I have developed the custom array list in java with a basic understanding Please let me know if there are any flaws in it that I can correct the same
First the POJO class
<...
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4
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115
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Get a random member of a container
It was not obvious how to get a random member of a container. So I wrote a function to retrieve it given a generator.
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3
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2
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Adding/removing songs to a playlist
This is a simple Java application, which adds songs to a playlist, removes songs from playlist based on indexes. A database is not used in this. I am creating dummy data through a ...
- 201
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1
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2k
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C++ ring buffer using some C++ 17 and coming C++ 20 std::span
When I heard about the new Linux I/O interface io_uring I searched about the ring buffer.
I then thought I may replace my safe queue which is base on C++ 11 ...
- 293
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1
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85
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Container that holds objects of various types, and can be searched for an object convertible to a given type
I built a container that can hold objects of various types, and look up an object convertible to a given type. I wrote something about my intended use-case here:
https://stackoverflow.com/questions/...
- 253
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150
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Code to pick buckets for a list of value
In my current project, I came across a scenario where there will be two sorted list of Decimal values. Let's call them ...
- 151
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3
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2k
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reverse a list of generic type
Q: Given a list, reverse the order of its elements (don't use
collections).
Here is my solution:
...
- 283
2
votes
1
answer
100
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transform list to array
Q: Write a method that transforms a list into an array (don't use
collections or already implemented methods in lists, make your own
method)
I've come with this solution:
...
- 283
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IList<T> implementation
I was wondering about the possibility to create an implementation of IList<T> that is faster than List<T> using C#, ...
user168452
3
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1
answer
342
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LinkedList Swift Implementation
Linked List Implementation in Swift
Swift 5.0, Xcode 10.3
I have written an implementation for a doubly linked list in Swift. As well, I decided to make the node class private and thus hidden to the ...
- 281
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A java program that gets a key-value pairs from a textfile, which should also print in a matrix/table like [closed]
I just want to get some advice about code optimization. How can I make this more OOP? How many class should I have for this kind of task? My code already works but I was told to use OOP in a way that ...
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75
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C++14 AtomicRoundRobinPool for sharing a pool of keys
The idea here is that we have some resource that is relatively very expensive to generate, but once we have a bunch of them in a pool, we can keep reusing them instead of generating new ones. "HTTP ...
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