Questions tagged [python]
Programming questions are off-topic here. Do not ask questions about how to write code in Python. However, conceptual questions about computer science are more appropriate. See our help center for the scope of this site.
226 questions
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Lambda calculus with keyword parameters?
Several programming languages support a calling convention wherein values are bound to parameters via a keyword, rather than position in a tuple of arguments. I'm curious whether there is any formal ...
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78
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Large-Scale Image Near-Duplicate Detection for Real Estate Dataset
I want to perform large-scale image similarities detection.
For context, I have a large database containing almost 13,000,000 flats. Every time a new flat is added to the database, I need to check ...
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125
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The problem of reachability in a directed graph, but all predecessors must be reached to reach a node
Let $S$ be a set of nodes belonging to a directed graph $G = (V,E)$. A vertex $v$ of $G$ is said to be reachable from $S$ if and only if $v \in S$, or if each predecessor of $v$ is reachable from $S$ ...
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94
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Flipping a single bit of Floating-points (IEEE-754) mathematically
I'm working on implementing a mathematical approach to bit flipping in IEEE 754 FP16 floating-point numbers without using direct bit manipulation. The goal is to flip a specific bit (particularly in ...
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134
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What other ways could be of representing an irreducible fraction without gcd?
My code for it:
from math import gcd
y = int(input())
w = int(input())
g = gcd(y, w)
print(f"{y// g}/{w// g}")
Could there be any other way of solving this problem without using gcd ?
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196
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How to select numbers with the same Hamming distance under certain conditions?
How can I find a non-exhaustive algorithm for the following problem?
In the $N$-base number system, there are exactly $ N^{(N+1)} $ numbers with $N+1$ digits.
I would like to select $N^2$ numbers such ...
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111
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How to write the Python Program for the following condition?
How to write a Python Program for the following condition:
Let me explain how I tried to write the code.
$a=$ int$($input$($'enter the first integer between $1$ and $9$'$))$
$b=$ int$($input$($'enter ...
user176748
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83
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Why doesn't this recursive Fibonacci function in Python give me a recursion depth error?
I have the following Python (3.12) code for finding Fibonacci numbers recursively, and keeping track of how many times the function is called.
...
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107
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For which languages can branching be determined by static analysis?
Python has methods like getattr() which can be used to branch arbitrarily at runtime. As a result, static code analysis tools can't be certain what functions a ...
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92
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Do edge lists have O(E) storage if default values are used for absent keys?
Ordinarily, edge list representations of graphs take $O(V+E)$ space, where $V$ is the number of vertices and $E$ is the number of edges. For example, consider a graph with 5 nodes and a single edge ...
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402
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When do we multiply or add the time complexities of loops?
I am confused about calculating the time complexity of the following function.
...
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173
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Using XOR operation, a MOD operation compute a function f(n)
I had a difficult assignment in my Data Structures and Algorithms class.
We need to implement a program that computes a function f(n) based on the following known values of n and f(n):
n : 9689 ...
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1
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154
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Improve performances of Gauss-Jordan (XOR-SAT) Algorithm?
In this question I was looking for an algorithm to solve what seems to be a XOR-SAT problem.
Let's consider this equation system :
...
- 295
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128
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Write an algorithm for finding the duplicated grades
I have an interesting real world problem. My brother is currently in school. The teachers perform the following procedure when giving him his grades. They take his list of grades ...
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93
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Generate product description from product specifications
I am looking for a python NLP library that can generate a proper product description based on product features provided to it.
Till now, i have tried transformers library and this is the code:
...
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130
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Coding the labyrinth solver
The question mathematically has been answered here: https://math.stackexchange.com/questions/4886084/guaranteed-graph-labyrinth-solving-sequence/4887473#4887473
To summarize, in an unknown strongly ...
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216
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How many different colors are possible to generate in the HSV Color Space using OpenCV?
I don't know if this post belongs in this site because I feel it might be a programming question, but also I feel it might be related to the way Color Spaces work, if it does't belong here I can ...
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236
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Can I speed up this multi-LCSS (Longest Common Substring) algorithm?
I'm creating a plagiarism detection algorithm in Python, which scores how much of document A has been plagiarised in document B, and returns all the copied sections in B that were plagiarised from A.
...
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2
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Find 1s in almost all 0 array using comparisons only
So, we are given a 100 long array, with 97 0s and 3 1s of which we do not know the locations. We must find them using only a compare function, which I managed to write (in Python):
...
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78
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Python Scikit-Learn transformation
I am trying to learn Scikit_Learn and build an ML model. I am learning from "Hands-On Machine Learning with SciKit-Learn, Keras & TensorFlow".
In Chapter 2, there is a review of an ...
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1
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163
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A floating-point rounding problem
I run the Python code below. x and y differ in their 4th and 5th number, and x has larger ...
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1
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152
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How does numpy.linalg.inv calculate the inverse of a matrix?
What is the algorithm behind this routine and is there documentation available for it?
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1
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157
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Repeated Substring Pattern
I've been working on the following challenge on LeetCode:
Problem:
Given a string s, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together....
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Identifying peaks at every cluster
I have a data set showing different clusters of data points and was attempting to find a way to get the peak of at every cluster. Comparing the moving average between a set of points does not work as ...
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493
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What is the practical use of list.clear() method in Python?
I was wondering if there is a reason behind clearing all the values in a list and reusing it, as opposed to deleting the list and creating a new one. Are there any practical advantages of using ...
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59
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Trying to model HIV using cellular automaton but can't replicate the results of some paper
There is this paper in which HIV is modelled using cellular automaton. I am trying to replicate this work but I am not getting the same results as the authors. In this paper the authors describe the ...
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77
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Auxiliary Space Complexity of Dictionaries whose Keys are Iterables of Variable Size
Recently, I began delving into complexity analysis with dictionaries. More specifically, I have been looking at auxiliary space complexity. For the most part, this type of analysis has been ...
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122
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fast estimation of the amount of unique combinations
Let's say I have a set of two columns - Name, Surname. I have a list of possible values for
Name -> Jacob, John
Surname -> Mayerson, Kindle.
I want to generate a set of unique combinations for ...
- 135
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2
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90
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Should I concatenate three lists together or use two separate while loops in Python? Which option offers a better runtime complexity?
In the context of adding sparse polynomials, you have two alternative approaches to combine the terms from two separate polynomials. One option is to use the line of code ...
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1
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894
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Why boolean value in Python is 24/28 bytes?
What is the reason for this behavior? Usually, in other programming languages, it is either 4/8 bytes, if I am correct.
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174
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Compute the intersection of two polytopes and its corner points
I am looking for a method in Python/MATLAB to calculate the corner points of polytope which is an intersection of a polytope with half spaces.
I have a polytope P1 of the form
-1 <= x0 <= 1
-1 &...
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2
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249
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Diffucuty in understanding code after a recursive call
This is an example algorithm of a recursive insertion sort I'm trying to understand. I've have tried understanding this with
the help of print statements (which I've commented).
...
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1
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77
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Combining chunks on an infinite grid into regions
I am working on an floorplan application where I save elements on an infinite grid in a sparse manner. Specifically, I have the following Python class representing a sparse grid (basically a ...
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125
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A practical issue in the code of HackerRank Restaurant problem
Problem Statement
Martha is interviewing at Subway. One of the rounds of the interview requires her to cut a bread of size $\ell \times b$ into smaller identical pieces such that each piece is a ...
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237
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Can halting problem solved by soft computation?
As far as I know, the halting problem means we can't create a program that checks whether another program is stuck or halt based on given input. This means, the program expects two inputs and one ...
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1
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857
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Design an algorithm to predict words based on a skeleton from a given dictionary
I'm working on an algorithm which is permitted to use a training set of approximately 250,000 dictionary words.
I have built and providing here with a basic, working algorithm. This algorithm will ...
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245
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Sympy does not recognise when two partial derivatives happen to be equal
I am trying to find the first and second-order partial derivatives of a function of four variables $S$ using pythons symbolic math package sympy.
The issue is that sympy does not automatically see ...
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Detecting if an object reached target points
I have an object that is moving towards target points and I want to determine when it will reach or pass through them. I receive points in real time, which represent the current position of the object....
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182
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Create a simple Neural Network of n layers in python from scratch with numpy to solve XOR example problem using Batch Gradient Descent
I'm a young programmer that was interested by machine learning. I watched videos and read articles about the theory behind simple neural networks. However, I can't manage to set it up correctly. I've ...
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248
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Why does Python behave so absurdly when dealing with numbers with decimal points?
r1 and r2 both are assigned 0.05 initially. If r1 is incremented by 0.01 in this way "r1 = r1 +0.01" we have 0.060000000000000005 as answer not 0.06.
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156
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Number of islands
In the counting number of islands problem, I noticed that one of the solution from internet is as follows
...
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2
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92
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Discarding lists of same elements
Suppose, I have a list of lists where multiple lists can have same elements. In my final output, I just want one list with the same element. An example is the following:
Input: A=[[1,2,0], [0,1,2], [2,...
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2
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212
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Speeding up an array search for duplicate
I was tasked with writing a function that finds the value of an element that is the first duplicate in an array to be encountered. For the array
[2, 1, 3, 5, 3, 2]
...
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409
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Can somebody explain to me the concept of mutability with respect to a NumPy array?
From the NumPy documentation:
"NumPy arrays have a fixed size at creation, unlike Python lists (which can grow dynamically). Changing the size of an ndarray will create a new array and delete ...
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Does an algorithm's space complexity include input?
Consider the Kadane's algorithm for finding maximum subarray within an array:
...
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571
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How sparsity term in loss function for sparse autoencoder is making hidden units inactive?
I am working on a Sparse Autoencoder but Andrew NG's notes are hard to understand.
My question is about the following equation: Loss Function.
In sparse autoencoder, the goal is to inactive some ...
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Finding all zero sums of length m and checking for zero subsums on an abelian group (generalization of the sub sum problem?)
Let $G$ be an abelian group. We say that $G$ has property $V_n$ if for every $m > n$ and a list $L\subset G$ of $m$ elements s.t. $\sum_{g\in L}g=0$ there is a proper subset $\emptyset\neq L'\...
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85
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Having a 2D matrix with three typed elements, how to efficiently cover one of the types and NOT cover the other one?
I have a matrix with three possible elements: A, B and C. The size of the matrix could be a maximum of 15x16.
$$
\begin{bmatrix}
A & A & C & A\\
A & C & B & C\\
A & C & ...
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226
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How can I convert the pseudo-code that solves maximum subarray problem to Python code?
I'm reading Algorithm Design and Application, by Michael T. Goodrich and Robert Tamassia, and sometimes the pseudo-code in this book doesn't make sense at all.
At chapter one they show us 3 solutions ...
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240
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Finding whether a point lies on the boundary of an geometrical object or not?
Suppose I have the mesh of an geometrical object (Interval in 1d, Region in 2d, Volume in 3d). How can I find out whether a point lies on its boundary or not?
I am looking for algorithms with ...
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