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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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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iterator that iterates over a file by paragraph [on hold]

I wrote the following iterator to tackle the following problem. I have the following string contained in a file called "example.txt": ...
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3answers
169 views

SkipLast of an IEnumerable<T> - Linq Extension

As my answer to this question, I came up with this solution: ...
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3answers
413 views

Generator iterator with push back function

In a compiler project for an LL(1/2) grammar, I have had a need for a generator iterator with a push back function. I have been surprised not to find any perfectly applicable solution (clean, simple, ...
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Using best practice with complex iteration

I'm new to Rust so I'm still learning how to use best practice in complex examples. Below is some code I've used in one of my programs, a simple implementation of a standard neural network. Here is ...
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1answer
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Email Generator

I've made a email generator, that uses a HTML template and replaces keywords in the template with information taken from a database. I'm looking to see if there is a way to improve the coding. ...
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1answer
51 views

C function to fully consume a Python iterator

I was reading into the proper way to consume an iterator on this question as well as here and I notices there is no actual proper function for this that clearly explains itself. Using: ...
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1answer
75 views

Iterable hashtable implementation in C

I'm just finished my version of iterable hashtable. I want to review code in general (code style, data structures, remarks about the algorithms) and I have some questions: I don't know how to ...
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1answer
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Most efficient way to loop through files using VBA Excel

I have a procedure for looping through all files in folders and subfolders starting at a folder which the user can select. The user can select both the source and target folder. I'm using Excel VBA ...
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1answer
31 views

Replace values in R data frame according to values in other data frame

I would like to change row names values from a first data frame if these rows names are present in another data frame, and change it to a corresponding value (defined in the second data frame). I ...
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5answers
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StreamIterable - create an iterable from a Java 8 Stream

This seems like an easy thing to mess up, so I'd be grateful if you could think of any edge-cases that I've missed. ...
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2answers
59 views

Iterating over a range of integer ranges in Java

My use case is this: RangeDemo.java: ...
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0answers
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Rust Iterator that correlates a slice with itself

In my effort to learn Rust I've tried implementing an Iterator that splits up a buffer in two halves, and correlates both halves by sliding them over each other with different positions (lags). You ...
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1answer
63 views

Sequence for Pre-order traversal of Binary Trees

I wanted to make a Sequence that can do a pre-order traversal of Binary Tree. Doing so provides automatically unlocks wonderfully useful methods, like ...
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2answers
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Simple linked list with two iterators

As part of the practice, I created minimalist linked list named SimpleList which can be iterated in two different ways: one element after another or by every second ...
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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 ...
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Count all vowels in string

For a homework assignemnt, I was asked to complete this CodeStepByStep problem. It's coded correctly and gave me a right answer. I'm just wondering if there's an easier way to solve this problem ...
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1answer
93 views

Find all starting indices in a string which are anagrams of a word

The task: Given a word W and a string S, find all starting indices in S which are anagrams of W. For example, given that W is "ab", and S is "abxaba", return 0, 3, and 4. My solution: ...
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String sequence in ES6

Given an unique string that represents a sequence of characters, the class should implement three methods (getNextChar, getNextString and the genSequence generator). How it works We give a sequence ...
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2answers
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Combining arbitrary number of lists inside json

I have some JSON where each key stores an array, and I need to combine all those arrays into a single array. My current solution doesn't seem the most friendly to review, but without ...
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1answer
93 views

Speed up fast poisson disk sampling generator in Python

I wrote a generator class which implements Fast Poisson Disk Sampling algorithm in Python. I did some optimizations like, x ** 2 -> x * x, using unpacking ...
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3answers
107 views

Linked list implementation C++

I hope this is the right way of doing things: I've previously posted a request for a code review and gotten feedback. Now I have new improved code that I would like a code review on again. Old: C++ ...
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2answers
110 views

C++ linked list iterator implementation

I'm a first year computer engineering student and would appreciate feedback on some code. I've created a linked-list with an iterator to be able to range for loops like: ...
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1answer
60 views

Optimizing quicksort

I created simple quicksort algorithm using iterators. I'm happy with implementation but not with its speed. Profiler tells me that the slowest operation here is ...
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3answers
903 views

Compute Convex Hull

The question asks to compute the convex hull of a set of 2D points. A convex hull is basically a series of consecutive line segments that suffice to enclose all the points in the area. In this ...
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0answers
51 views

itertools.produce reduced and filtered

I need to generate list of all allowable test combination values of of actor, action and ...
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3answers
3k views

Pythonish integer range in Java

Introduction After getting stuck with a Pythonish integer range in C++, I rewrote the facility in Java. In Python you can say: ...
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A Java Iterable over multiple arrays

GlueArrays is used for iterating over an array of arrays, and it looks like this: Main.java ...
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1answer
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Short analogue of Riffle[] accepting two blocks

I have an array of some elements that I need to loop through (i.e. execute some block A on each element) but between them I have also to "clean up" (block ...
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3answers
2k views

Decoding assembly instructions in a Game Boy disassembler

I am coding a game boy disassembler in C++. The program (simplified here) converts a vector of byte into an assembly instruction and print it. To do so, it iterates through the vector of bytes (char)...
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1answer
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Merging (not removing) duplicated elements in a vector

There's a struct named Player containing name and stat: ...
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2answers
101 views

Pythonish integer range in Java - follow-up

(See the previous iteration.) I have refactored the Range; now it looks like this: Range.java: ...
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2answers
83 views

Infinite and countdown counters

I'm refactoring my scheduler and for one of its triggers I need an endless counter that would automatically restart. Since this is a simple and very common task I don't want to ever have to implement ...
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3answers
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My implementation of a for_each function that traverses a std::container by some step size integer N

As my answer to Iterating over an odd (even) elements only in a range-based loop, I wrote this function, with the following driver program and output: ...
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1answer
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Rust version of basic functional prime stream - can this be made less clunky?

I'm looking at implementing the basic functional not-quite-Eratosthenes prime stream in Rust. I like to try it when I start learning a language. Here's the bog standard Haskell version: ...
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2answers
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Custom iterator for a linked list class

I have made a LinkedList class. This is a singly-linked-list and I want to make a forward_iterator for this class without using ...
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1answer
88 views

Iterating over different Objects which are ordered by index number

I am currently working on a bigger project where I found a part of it which seems very ugly to me from the code. I stripped out the algorithm and made a working code, so it can be reviewed. I have ...
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1answer
286 views

Applying multiple php FilterIterator instances in a cascading fashion

I wrote an implementation of php FilterIterator objects that allows me to apply them in a "cascade" way, so I can finally obtain an array of objects which is the ...
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0answers
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An iterator returning all possible permutations of a list in Java - follow-up

(See the previous and initial iteration.) My main attempt here was to get rid of monolithic code and split the implementation into smaller methods when applicable and do more extensive commenting. ...
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1answer
8k views

ArrayList for Shop implementatin

Problem statement: Design a system for the following scenario: An item list contains item code, name, rate, and quantity for several items. Whenever a new item is added in the list ...
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3answers
510 views

Python generator for “barely obtuse” triangles (Project Euler 224)

I am trying to solve Project Euler Problem 224: Let us call an integer sided triangle with sides a ≤ b ≤ c barely obtuse if the sides satisfy a2 + b2 = c2 - 1. How many barely obtuse triangles ...
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2answers
81 views

Python grouped iterator

I wanted to write an iterator that would split items up into groups, so i can bulk insert into mysql without crashing or overwhelming the server. This is the implementation I came up with. I am ...
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0answers
40 views

Iterator that groups elements of its source

I wrote an iterator to access the pixel in an packed image. It works, but it is slow. 1.Are there any mistakes that can be avoided and might lead to better speed? 2.Are there any pitfalls that ...
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1answer
74 views

File names to database table

I have files in subfolders on a network drive. I want to create a list of files, and insert that list into an Oracle table. I can successfully iterate through the files in the subfolders and do the ...
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1answer
51 views

Class representing digital PLC address

I have a project where I work with digital addresses for a Programmable Logic Controller (PLC). The requirement is that the user gives a start address e.g. 1000.0 and then for example the next 20 ...
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2answers
144 views

Walking directory tree like python does

I like python's os.walk and I was missing it in C#. It's a very convenient API so I thought I create my own utility that does something similar. The original API ...
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2answers
109 views

Finding the common iterator category in C++

I created a template trait which finds the common iterator category between a set of given iterator categories. More specifically, it's a class with a member type alias to one of the iterator tags ...
4
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1answer
58 views

General use multi-dimensional container using operator[]

This is a followup to a previous question of mine on same subject. Context I want to have a tool that allows to simulate as much as possible a C++ standard container for a multidimensional ...
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1answer
35 views

Finding the Original Fractions from Rounded Decimals

The data I'm using is summoning rates from a gacha game, One Piece Treasure Cruise. The game provides the probability of getting a certain character in percents rounded to the nearest thousandth. ...