Questions tagged [python]

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How to approach backtracking when using immutable types (Python)?

In Python when we are building a recursive algorithm that uses backtracking a mutable type such as a list is great to use. It can be modified at each call in our recursion tree, then returned back to ...
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0answers
17 views

Knapsack problem in real life

My task is to develop an algorithm for the optimal arrangement of cylindrical objects in cartons. The algorithm is to have the task of placing as many products as possible into cartons, at the same ...
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4answers
35 views

Quadratic equations using 2 different approaches

I am reading Mark Newman's Computational Physics and at chapter 4 page 133 in Exercise 4.2 he asks a) Write a program that takes as input three numbers, a, b, and c, and prints out the two solutions ...
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8 views

When you override __eq__ in a class, do you also need to override __hash__? (Python3) [migrated]

I'm making a node class in python which I will be storing in a min-ordered multi-tree structure. I overrode the eq method which tests for equality by comparing two unique integer instance variables. ...
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1answer
25 views

How does a=2 twice in this code sample? [closed]

I am just starting out learning code. The output of the following code is OOOXOXOO, but I don't see how X can be printed twice. How does a=2 more than once? ...
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1answer
99 views

Could we define the decimal notation of a natural number as a series of operations applied to 0? [closed]

People have made mistakes. For that reason, there probably is a demand by some people for a computer program that's easier to verify makes the calculations properly. I think that according to the ...
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2answers
54 views

How can the length of a string be $O(\log n)$?

I have just started learning about time complexities and am currently reading Logarithmic Complexity. Here's an example of a piece of code which is $O(\log n)$: ...
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3answers
3k views

Which other programming languages apart from Python and predecessor are out there using indentation to define code blocks? [closed]

Python quite famously uses indentation to syntactically define blocks of code. (See Compound statements in the Python Language Reference). After years of using Python I'm still intrigued by and very ...
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0answers
99 views

Mixed Integer Linear Programming application problem

I have a Mixed-Integer Linear Programming question. There's this game called Islanders. Pretty graphics, it's about maximizing your score building a small city in a confined island. Here's a quick ...
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0answers
22 views

Good algorithm to compress down connections of graph nodes?

I have a collection of graph nodes which are connected to each other. I wrote a DFS algorithm to recursively search the connectivity of the graph to find all connected nodes, however due to the size ...
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1answer
45 views

Big Oh Time Complexity Involving 'for i in range(n)' [closed]

Given the code below and the comment analysis: ...
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0answers
329 views

Draw 3D bounding box of object in 2D image OpenCV

Recently I have been interested in Computer Vision and I am now experimenting with OpenCV in Python. I have done some research but haven't really found what I am looking for. Therefore I try to give ...
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1answer
122 views

Compute hash value according to multiplication method

In "Introduction to Algorithms" by C. E. Leiserson, R. L. Rivest and C. Stein (ISBN: 978-0262033848), p. 264 they state this: I get everything but the last part stating $h(k) = 67$ ...
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0answers
43 views

How to perform particle swarm optimization clustering of results obtained from tf-idf vectorizer?

I have a collection of news articles. I have performed tf-idf operations on them. I am using python as programming language so it was just the use of TF-IDF vectorizer function. I now have the ...
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0answers
70 views

Random Forest - Conditional Permutation Importance

I've been looking for the most unbiased algorithm to find out the feature importances in random forests if there are correlations among the input features. Besides the most commonly preferred ...
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0answers
15 views

Cluster with categorical / ordinal

i have a dataset with movies review. I wish cluster my element but inside i have a categorical / ordinal values. i seen that exist: MCA (Multiple Correspondence Analysis) https://www.utdallas.edu/~...
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18 views

how can I write an algorithm in python that converts a natural number n into base b? [duplicate]

I only know simple python but I'm not sure how to write an algorithm that takes values n and b, where n is a positive integer and b is the base, and converts n into base b. Note b<=10.
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0answers
19 views

How to go about designing a quiz that changes difficulty based on user performance?

I thought about using a machine learning algorithm to learn the performance patterns of the quiz taker and model the next quiz based on how he/she performed. So each question will have a difficulty ...
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0answers
19 views

If statement not capturing the conditional I'm seeking [closed]

I'm working on a hw assignment, and my if statement isn't working the way it's intended. This is an ATM machine project. I've already gotten the program to read the csv file and stored it into a ...
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1answer
41 views

Ant Colony optimisation for finding subsets with ~0 sum

I have a set A = [x1, x2...xn] where xi in R (real). I need to find all non intersecting subsets with subset sum ~0 (approximately equal to zero). Since the set can have non zero real numbers, I have ...
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0answers
21 views

Composite and Non-Composite User-Defined Data Types

I have a learning resource which claims the following about user-defined data types Non-composite include: Enumerated Pointer Composite include: Record Set This confuses me, and I would ...
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1answer
57 views

Does this sorting algorithm already exist? And if so, what is its name?

I created this algorithm off the top of my head this morning. It has one loop, therefore it has a time complexity of O(n) and only stores two variable during loop so it has a space complexity O(1) ...
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1answer
29 views

After how many iterations will an integer circle back to 0 in Python? [closed]

If this question is completely garbage I apologize because I am new to CS and haven't understood at how programming languages (Python specifically) work. I was reading about how in a standard two-...
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1answer
27 views

My code works, But how do I make this code run in a deterministic time?

The Problem: Given 3 inputs Bounce, Ball drop height, and ball view height. How do I calculate the number of times the observer can see the ball pass. So my code gives correct output, but it takes ...
2
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1answer
76 views

Minimum cost node cut

I am interested in solving the following problem: Given an undirected graph whose vertices are weighted, find a subset of vertices of minimal weight whose removal disconnects the graph. Is there ...
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2answers
240 views

Help with Time Complexity

Suppose we have the function below: ...
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1answer
172 views

What is the procedure to find the time complexity of python program? [duplicate]

Is there any kind of function which is used in python to calculate the time complexity of another function?
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0answers
29 views

Is this solution is bad for the coin change problem? [closed]

was doing coin change problem as an assignment(didnt know before), after came with this solution i checked the solutions available couldnt find a similar one like this, just curious. removing the ...
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1answer
64 views

Finding a minimum weight path with certain restrictions

I have a directed weighted multigraph whose vertices are sets of URLs. We add to this multigraph all edges of the form $i\to j$ where $i\subset j$ (such edges are of zero weight), where $i$, $j$ are ...
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1answer
244 views

Why is this n^2 growth?

I am attempting to understand the growth of the following algorithm, which is described as $n^2$ growth in the book I am reading: "... performs of the order of $n^2$ steps on a sequence of length $n$....
3
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1answer
53 views

Why does parallelising slow down this simple problem against looping through all the data?

I've been using multiprocessing and parallelisation for the first time this week on a very large data set using 32 CPUs. I decided to explore it for a smaller task just to see if I could learn ...
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1answer
48 views

A problem about slicing and indexing in numpy in Python [closed]

I learned that in numpy, given a vector, slicing and indexing could give different results. I ran the following codes: ...
2
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1answer
326 views

How can I optimize 3 variables in order to maximize the end product?

I am in the process of making a cryptocurrency trading bot. Currently, I am doing backtesting over a period of 7 months in which I provide a portion of historical data as if it were in real-life. By ...
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1answer
459 views

How to use Latin hypercube sampling with fixed points?

I use Latin hypercube sampling to select what point to evaluate my function. As evaluations take a lot of time, I want to limit the time by adding already evaluated points. I thought about taking the ...
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1answer
1k views

Python: Clustering based on pairwise distance matrix [closed]

I have a matrix which represents the distances between every two relevant items. For example, M[i][j] holds the distance between items i and j. My next aim is to cluster items by these distances. I ...
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40 views

how to build logical representation from dependency tree

I'm trying to build logical representation from dependency tree with python. i created the tree with stanford parser. How can I derive logical presentation from it using Lambda-calculus?
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0answers
41 views

Van Emde Boas Cluster recursion

I have been trying to implement a Van Emde Boas tree in python, but I'm having trouble understanding how exactly it works. In the notes here, It states that the summary of a VEB structure is another ...
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0answers
29 views

Open source implementation of Multiscale Combinatorial Grouping [closed]

I would like to use Multiscale Combinatorial Grouping for my PhD research. However, I am restricted to use open-source implementations and this one runs on Matlab. Does anyone know of an equivalent ...
3
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1answer
191 views

Understanding Applicative Evaluation Order with the Z-Combinator

I am trying to understand how the Z-combinator (Y-combinator for applicative order languages) definition came about. As Python is applicative I am using Python for this. So I know Python's evaluation ...
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0answers
34 views

What data structure would be best for a code cross referencer?

I want to write a JavaScript cross referencer (in Python) that will build a cross-reference of JavaScript functions for a given input file. I am trying to think of what Abstract Data Type would work ...
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0answers
27 views

Unusual function - operations on lists / sets - possible optimization

I have a problem. Below I present a function in Python. ...
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1answer
297 views

Control of the combinatorial aspects of a dynamic programming solution

I am exploring how a Dynamic Programming design approach relates to the underlying combinatorial properties of problems. For this, I am looking at the canonical instance of the coin exchange problem: ...
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1answer
33 views

How is ReLU used in machine learning functions

I've seen how sigmoid would be used in machine learning sigmoid(dot(activations, weights)-bias) like this ^ but sigmoid makes sure your values are between 0 and ...
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1answer
39 views

Using computer vision instead of algorithms?

I have been thinking of a problem i have here with a calendar scheduler where i basically want to split a year into seconds and have access to the dataset of whole year. In this year i assign blocks ...
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0answers
24 views

Need a game with AI techqniques [closed]

I want to learn Artificial Intelligence techniques by writing a game (or maybe any fun project). Can you suggest any games? Consider that I'm a beginner in AI, but have basic knowledge Algorithms and ...
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2answers
20 views

Distinguishing between side-by-side liquid streams

I'm new to computer vision and am looking for advice. I'd like to perform computer vision on a spiral system, in this system a down flowing liquid separates into different regions based on density: ...
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1answer
589 views

list('\a','\b','\c') prints '\x07', '\x08', '\\c' [closed]

In python3.6, I tried In [60]: a = '\a' In [61]: b = '\b' In [62]: c = '\c' In [63]: l =[a, b, c] If test l ...
2
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1answer
262 views

Conditional Shortest Path Through Weighted Cyclic Directed Graph

Vertices in my graph are composed of {name, category} where category is one of {red, grn, blu, ylw}. Edges in my graph are weighted and directed. In the visualization, the thick end of the edge ...
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0answers
37 views

Are the terms “Language Implementation”, “Runtime” and “Virtual Machine” synonymous?

To describe the implementation of a dynamic programming language, I have seen the terms "Runtime" (e.g. Security transparency in the Python runtime), "Virtual Machine" (Python Virtual Machine (PVM), ...
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2answers
584 views

Determining time complexity of this function in python [duplicate]

I would like to determine the time complexity of this function, in $\mathcal{O}$-Notation. ...