Questions tagged [iterator]

An iterator is an object-oriented programming pattern which for the most part functions similarly to a pointer to an object inside a collection with the added ability to traverse through the collection in a defined manner, agnostic of the actual implementation or even object addresses in physical memory. Iterators may be further limited in particular traversal directions.

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Random Access Iterator Implementation

(This is the Non-const version, I have to implement the const one too). Could someone please review this implementation? This is made for std::vector I'm unsure whether I respected all requirements ...
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Input Iterator implementation

I need some review on my implementation of input iterator. I am currently re-implementing std::vector, and need input_iterator for a specific constructor. Any criticism is much appreciated! Thank you. ...
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1answer
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Cyclic generator with access to current local state and executes callback after each cycle

I'm working on a Python class that is a cyclic generator, like itertools.cycle, but it offers access to its current state and executes a callback after the ...
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wrapper class for random access iterator to hide template method implementation from header file

I have a set of template functions that have itrator types as template parameters, so can be used with any kind of iterators. std::find can be a good example. Also ...
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Const wrapper for iterator

Edit: added clarification for why I want this, and updated the code since I don't have any answers yet I have a C++11 array-like class which (can be) a wrapper around a random-access iterator. Index-...
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Shorten dict comprehension with repeated operation

dc = {line.split('=')[0]: line.split('=')[1] for line in txt} Below avoids duplication but is even longer: ...
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Convert array of u32 to Vec<u8> in Rust

In Rust, I want to take an array of u32 values, convert each to four bytes in big endian, and concatenate them to yield a ...
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Counting words from stored .md files

The following searches recursively for all the mark down files - i. ending with the extension .md - inside a folder. It then stores the text of the files in an ...
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1answer
39 views

Get all routes that start with rt_

The code reads all my routes and return to my JQUERY AJAX the names of the routes without duplicates and just those that have "rt_" prefix. ...
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1answer
160 views

Rust shortest way to find the maximum product of a fixed length substring

I'm trying to code in a Rust a function, that gives the maximum product of adjacent digits. So given the string 123456789, with 3 adjacent digits, the maximum is <...
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base64 iterators

Was a tiny bit bored reading authentication protocols. Needed to clear the mind and read some base64 encode text. So I implemented these iterators that will encode or decode base64 text. Not sure ...
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Async linked list to and from async iterable

I'm working on some stuff that works better with (immutable async) linked lists such as this: ...
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1answer
53 views

Extending method chaining IEnumerable with Add..If

I'm trying to write an extension (method chaining) for playing around a bit. What I made work is an extension to add an item to the list (what is pretty easy): ...
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1answer
93 views

Generate binary image using coordinate vectors

I have a matrix M of size [n_rows, n_cols] and a list of x and ...
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Rust Iterator repeat_each

repeat_each transforms an iterator by repeating each value count times. It should be equivalent to ...
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0answers
209 views

Deep map, Python

Goal: apply fn to every element of an arbitrarily nested iterable (tuple, list, dict, np.ndarray), including to iterables. Ex: ...
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2answers
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Deep len, Python

Goal: find total number of elements in a nested iterable of arbitrary depth. My shot: ...
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2answers
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Fibonacci iterator

I've implemented the following Fibonacci iterator: lib.rs ...
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1answer
53 views

Ensure queue is in ascending order

The program reads in a queue of integers and returns determines whether or not it is valid (ascending). How can this code be improved? I assume iterator include statement is unnecessary? ...
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1answer
51 views

Iterator-Pattern for an iterator that returns one objects that changes

I wrote an algorithm that returns all k-sized subgraphs of another given graph. Because I don't want to make the runtime of the next() call of the iterator depended on k, I don't want to return a new ...
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4answers
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Exercise: Design a Stack

Exercise: Design a Stack A Stack is a data structure for storing a list of elements in a LIFO (last in, first out) fashion. Design a class called Stack with three methods. ...
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1answer
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`zip` operator to iterate on multiple container in a sign

I worked out a zip operator similar to Python's, because I didn't find one in std. It allows to use range-based ...
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1answer
77 views

template iterable numeric range class with multiple min/max inclusion modes

Problem my code solves: Lack of lightweight numeric range classes which can tell if arbitrary values lie inside them, supporting more than just simple exclusive max modes and integers, and that ...
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Splits up two comma separated items, if they exist

This method splits up two comma separated items, if they exist, and increments the amount if the are already in the list; otherwise add the item to the list I want to know if this code can be ...
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1answer
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Compare length of iterator with as few `next` calls as possible. How can I deduplicate this code?

I'm writing a few simple functions that compare the length of an iterator to an integer, returning as early as possible. Right now I have: ...
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1answer
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c# QuadTree yielding properly [closed]

I have implemented a QuadTree of my own, and I'm afraid I didn't use yield properly when I query my tree, my fear is that I create O(HN) iterators. Could you direct me how to better improve the ...
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Populate a list with combinations of one- and two- object functions

I have a nested set of for loops which achieves the desired outcome, but I don't know if it is the most efficient / pythonic way of populating this list. I would ...
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Manipulating list values in python

I wrote a function that I use to preprocess pandas dataframes before running them through a machine learning model. The function works perfectly, however I don't think it's the most pythonic way to ...
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1answer
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Summation Over Lines in a File (Advent of Code 2018 Day 1)

Preface: I am learning Rust through the Advent of Code The task is to read lines from a file, parse each as an integer, then provide a summation of all the numbers. My solution looks like this: <...
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1answer
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Iterate through Expression Tree

I'm trying to build an iterator (enumerator) that can select specific elements in an Expression tree by traversing the tree and deferring further iteration until ...
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C++17 zip iterator compatible with std::sort

Here are ~100 lines of code implementing three classes (ZipRef, ZipIter, Zip) which should ...
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874 views

Iterator for traversing a tree [v2]

this is an update of the implementation after I followed the feedback from Iterator for traversing a tree. After that I did changed quite a bit on the design and decided to ask for another round of ...
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1answer
87 views

Iterator for traversing a tree

What I want to achieve is the following: ...
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1answer
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Paginate IEnumerable<T> sequence

I used the following to split sequence into batches: ...
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1answer
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Bidirectional numeric (floating point) sequence iterator

I wanted a neat iterator that will always give me neat sequence of step spaced numbers. This is what I came up with, but I am a bit skeptical that I covered all ...
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Combining two nested for loops into one [closed]

Description What this does is it takes a randomly generated 64x64 stack and checks for overlap within the 64x64 array. Here is an example: https://imgur.com/a/kkPRzhn. Each color is its own ...
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1answer
216 views

A simple priority queue in Java via linked list sorted by priority keys

Now I have this very simple priority queue. add and changePriority both run in \$\mathcal{O}(n)\$ and ...
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1answer
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A GapHelper static class to create unique (non-existing) size restricted names

I am working with a 3th party library which has following interface defined for a processing task: ...
7
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1answer
248 views

Map unique raw words to a list of code words

Problem Write a function that replaces the words in raw with the words in code_words such that the first occurrence of each ...
3
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1answer
72 views

Aggregation on list forEach and maps improvals

I am using a function in a SpringBoot @RestController, with Lombok This function is an intermediate result that permit me to do an aggregation between two classes. This 2 classes are: ...
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1answer
148 views

c++ python like range function to use in for loops

It's a simple range function that works like python range and it is only a syntactic sugar for the usual for loop if we want to operate on numbers in the range from 1 to 10 (1 ... 9) we use this code ...
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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 ...
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2answers
328 views

Doubly-linked-list implementation in C++

I am fairly new to C++ and have been trying to make a doubly-linked-list class that imitates std::list (though not all of it). I'd appreciate if someone can look at my code and let me know if I have ...
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2answers
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A basic trivia app

The app grabs 10 questions from an API, displays them one by one with 4 multiple choice answers. These answers are clickable buttons that alert to whether the answer is correct or not. Finally the ...
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2answers
415 views

Python-style Generator in Java

I have implemented Python-style generators within Java. I might be reinventing the wheel here, but I feel that the ability to define a Generator with an anonymous class is the most flexible approach. ...
2
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1answer
71 views

C++ singly linked list with iterator

I have written a simple singly linked list in C++. I have previously had a data structure in an interview criticised for being too C-like (no iterators and using new/delete) instead of smart pointers. ...
2
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1answer
151 views

Add method to Ruby's Enumerable module that produces every nth element

The task is to enhance the Enumerable module with a method nth(). The method shall create a new list, which contains every nth-...
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0answers
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General algorithm to calculate sums of all subsets of a given sequence of numbers

Background A recent question Print sums of all subsets made its way to the Hot Network Questions list. The problem is simple: Print sums of all subsets of a given set Given an array of ...
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2answers
79 views

Filename sequencer with outdated C++

My path to learning C++ has been a rough one. Currently, I'm writing a project and my knowledge is very outdated. While I can write code that accomplishes the tasks required, I'd like to improve and ...
2
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2answers
60 views

Implementation of enumerate

I'm trying to implement the enumerate built-in using iterators. So far it works but for unordered objects, such as sets or dictionaries, I'm not sure if this implementation is considered valid, ...

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