Questions tagged [python]

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12 views

Good books on python for beginners [closed]

I want to learn python programming language by my own. Can someone suggest me some Good books(for beginner) for that?
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15 views

How do i code Steepest Descent in python? [closed]

I am very confused and really need help to code with Steepest Descent method. I have a pseudo code for it( see picture).
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19 views

Regex Questions?

I need to match all words having two adjacent vowels that differ. I did this /\b(?=\w*([aeiou])(?!\1)[aeiou])\w+/ but I am not allowed to use the ?! and it needs to be done in as few characters as ...
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58 views

Can this graph-ordering problem be solved with LP?

I have a modelling problem that I am trying to solve with LP. (More specifically, in Python using PuLP or Pyomo). I am not terribly knowledgeable in this area and have been struggling to find the ...
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absurd output on a trivial function in python [duplicate]

k=1 while k!=0: x=float(input('Enter x:')) op=(1/(1+x))+(1/(1+(1/x))) print(op) I tried to test this function on python, clearly the output should ...
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1answer
30 views

How to check rapidly if an element is present in a large set of data

I am trying to harvest scientific publications data from different online sources like Core, PMC, arXiv etc. From these sources I keep the metadata of the articles (title, authors, abstract etc.) and ...
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3answers
960 views

Space complexity for storing integers in Python

So I was watching this mock interview by an Airbnb engineer on interviewing.io (https://youtu.be/cdCeU8DJvPM?t=1224) and around ~20:11 seconds he raises an interesting point. The question that the ...
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1answer
40 views

Concise Way To Specify The Space Of All Python Programs Under A Certain Size And Running Time?

Given the grammar of the Python language, is there a concise way to specify the space of all possible (and correct) Python programs? To avoid the underlying halting problem, the specification would ...
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21 views

How to compute the predecessor-subgraph in all-pairs-shortest-paths algorithm?

The following slow algorithm (implemented from CLRS book) which runs in $\Theta(V^4)$ works fine for computing shortest paths distances: ...
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65 views

Consider vectorization and for loop, do both approaches have the same time complexity?

I am learning this post Fast computation of nearest neighbors is an active area of research in machine learning. The most naive neighbor search implementation involves the brute-force computation ...
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53 views

Is Python's Grammar in a known Category between CFG and CSG?

I have a high level understanding of formal languages and grammars, and I'm familiar with the four major types of grammars in Chomsky hierarchy. I was interested in knowing the classification of ...
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1answer
20 views

Complexity of iterative exponentiation

I've watched multiple videos and read articles about recursion but I'm still confused. I've got this problem here but I'm unsure how to answer it: The following function calculates $x^n$ ...
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1answer
35 views

Are there any benefits of implementing the Fisher–Yates shuffle algorithm from tail to head instead of head to tail?

I was looking at the Fisher–Yates shuffle algorithm and followed the Python implementation for it. Python starts from the end of the array to the start. Looking at the algorithm I didn't see any ...
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13 views

Selecting right cartons for meeting demand (retail supply chain)

I am working on an inventory allocation problem and I could use some help figuring out an optimal solution. Let's say a retail chain's warehouse stores inventory in cartons (physical boxes). Each ...
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1answer
39 views

Intuition behind this specific algorithm for time series

Going through the EPI book and I need some help understanding this part. There's a problem, 5.7, that deals with buying and selling twice over a single time-series in order to maximise profit. The ...
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31 views

How to implement minimization of maximum regret?

We run a report, but for one of our big clients, it is taking too long. There is a loop where it loops for a list and fetches it upstream 1by1. We're making this a bulk operation now, but some items ...
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0answers
69 views

On teaching Kolmogorov complexity with Python and the complexity of composed strings

The setting of this question is a bit long-winded, but please bear with me. This fall I will be lecturing a course on mathematical information theory, and on a few lectures we will be discussing ...
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1answer
36 views

I am looking for an algorithm that can find the best possible combination of inputs, in order to determine the optimum output

So as the title poorly implies, I'm looking for an algorithm that can accomplish the following task (as an example): Given the inputs A(1:100), B(1:100), C(1:100), that can take on any value between ...
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2answers
55 views

What is the official name of a specific type of combination algorithm

Say that I have the following set of variables: [A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z] The values represent a list of variables from a dataset. ...
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0answers
72 views

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

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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240 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
57 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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1answer
26 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
101 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
72 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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157 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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26 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
55 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
751 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
134 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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55 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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197 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
16 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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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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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
59 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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160 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
31 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 ...
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1answer
163 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
355 views

Help with Time Complexity

Suppose we have the function below: ...
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1answer
180 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
30 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
139 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
247 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 $n$....
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1answer
55 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
62 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: ...