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Questions tagged [recursive-datastructures]

A recursive datastructure is a datastructure (e.g. a struct or class) that contains one or several references to instances of the same datastructure as a member.

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Parse Directory Structure (Strings) to JSON using PHP

I have an array of file-path strings like this videos/funny/jelloman.wmv videos/funny/bellydance.flv videos/abc.mp4 videos/june.mp4 videos/cleaver.mp4 audio/uptown.mp3 audio/juicy.mp3 fun.wmv jimmy.wmv herman.wmv End goal is to get them to…
Ecropolis
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Scope of mu (μ) bindings in type theory

A list in Haskell might look like this: data List a = Nil | Cons a (List a) A type theoretic interpretation is: λα.μβ.1+αβ which encodes the list type as the fixed point of a functor. In Haskell this could be represented: data Fix f = In (f (Fix…
user2023370
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Representing a directory tree as a recursive list

I am stuck with a certain task. What I want is a function that, given a directory path, would return a recursive-list as an output. The output should be of the form myList$dir$subdir$subdir$fullFilePath So basically I want to represent a directory…
Karolis Koncevičius
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PHP RecursiveIterator traversing

I have a structure representing a form and I want to iterate it using RecursiveIterator. The problem is this only returns the top-level questions. What am I doing wrong? Whole form: class Form implements RecursiveIterator{ private $id; …
cypher
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How to create a recursive data structure value in (functional) F#?

How can a value of type: type Tree = | Node of int * Tree list have a value that references itself generated in a functional way? The resulting value should be equal to x in the following Python code, for a suitable definition of Tree: x =…
Muhammad Alkarouri
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Recursively dir() a python object to find values of a certain type or with a certain value

I have a complex Python data structure (if it matters, it's a large music21 Score object) which will not pickle due to the presence of a weakref somewhere deep inside the object structure. I've debugged such problems with the stack trace and python…
Michael Scott Cuthbert
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Why do initial algebras correspond to data and final coalgebras to codata?

If I understand correctly, we can model inductive data types as initial F-algebras and co-inductive data types as final F-coalgebras (for an appropriate endofunctor F) [1]. I understand that according to Lambek's lemma the initial algebras (and…
Dan Oneață
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Building a nested tree-like structure in Python using recursive or iterative approach

I have been trying to build a nested tree-like structure for two days and decided to ask here for help. Suppose I have data like this: rows = [ {'Year': None, 'Region': None, 'Country': None, 'Manufacturer': None, 'Brand': None, 'Sales': 25}, #…
user1330974
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Insert node at the end of linked list

There is a simple iterative solution for these kind of problems. Node Insert(Node head,int data) { Node newNode = new Node(); newNode.data = data; if (head == null) { return newNode; } Node current = head; while…
CodeYogi
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A data structure for Logical Expressions in Haskell

I try to create a data structure for working with logical expressions. At first glance, the logical expressions look like Trees, so it seems reasonable to make up it from trees: data Property a = And (Property a) (Property a) | Or …
Sergey Sosnin
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What is an infinite scaleless quadtree called?

2D spatial indexing question: What do you call a data structure that is essentially an infinite* quadtree whose nodes contain neither absolute coordinates nor absolute scales -- in which the coordinate system of each node has been normalized to the…
Todd Lehman
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Is there an elegant way to have functions return functions of the same type (in a tuple)

I'm using haskell to implement a pattern involving functions that return a value, and themselves (or a function of the same type). Right now I've implemented this like so: newtype R a = R (a , a -> R a) -- some toy functions to demonstrate …
Lily
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Recursion versus manual stacks - Which is preferred in which case?

A recursive program creates a stack internally, and causes the users to write less code. Are there any cases where recursion is actually preferred over manual stacks for the reason other than mentioned above? EDIT 1: In what way is dynamic memory…
Aquarius_Girl
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How to create a recursive structure in ASP.NET MVC

I have a categories table which has three fields: Id, Title, and ParentId. I'd like to create a recursive hierarchical structure of my table (a tree) in a cshtml file. I'm new to ASP.NET MVC and I don't know how to do that, because there is no…
Saeed Neamati
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How can I walk this type with a recursion scheme instead of explicit recursion?

Consider this code: import Data.Maybe (fromMaybe) data MyStructure = Foo Int | Bar String MyStructure | Baz MyStructure MyStructure | Qux Bool Bool MyStructure MyStructure deriving(Eq,Show) makeReplacements :: [(MyStructure, MyStructure)] ->…
Joseph Sible-Reinstate Monica
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