Questions tagged [python]

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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 ...
EngineerP's user avatar
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1 answer
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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 ...
Rocky's user avatar
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1 answer
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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?
oogabooga's user avatar
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22 views

How do one decide topic for first data analysis project?

Suppose an absolute beginner (in the field of data analysis/data science), which is indeed my case, has decided to create a project for his/her resume. These are the skills he has learnt: Python(...
Swayam Jha's user avatar
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Networks and Internet Systems

I'm currently preparing for a final exam in Networks and Internet Systems. I don't have a large background knowledge on the topics, so I'm attempting to use python to approach the majority of question ...
Kate's user avatar
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2 votes
1 answer
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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....
Ariana's user avatar
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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 ...
Nader's user avatar
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1 vote
1 answer
54 views

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 ...
Akshay Katiha's user avatar
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0 answers
33 views

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 ...
Max's user avatar
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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 ...
LateGameLank's user avatar
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1 answer
52 views

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 ...
lapots's user avatar
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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 ...
alefvanoon's user avatar
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1 answer
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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.
kjkjkjkjkj's user avatar
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1 answer
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compute the intersection of two polytopes and it's 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&...
Möbius's user avatar
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1 vote
1 answer
84 views

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). ...
river_bell's user avatar
0 votes
1 answer
29 views

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 ...
Mate de Vita's user avatar
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Approach for the fake data generator that needs to maintain an order and referential integrity

I have a Python data generator capable of generating SQL-like relational data with primary and foreign key relationships, composite keys, and partial keys. Currently, I store this data in-memory using ...
lapots's user avatar
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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 ...
Math-Learner's user avatar
-2 votes
4 answers
120 views

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 ...
Muhammad Ikhwan Perwira's user avatar
-1 votes
1 answer
229 views

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 ...
driver's user avatar
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1 vote
1 answer
99 views

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 ...
G-Shillcock's user avatar
-1 votes
1 answer
55 views

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....
theateist's user avatar
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0 answers
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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 ...
NolanGio's user avatar
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2 answers
105 views

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.
Pulakesh Bag's user avatar
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0 answers
5 views

Reproducible research (published papers) about e-commerce or fashion

I am looking for reproducible research (published papers) about e-commerce and/or fashion which deals with exploratory data analysis, hypothesis testing and regression or ANOVA. This reproducible ...
Yumunus's user avatar
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3 answers
78 views

Number of islands

In the counting number of islands problem, I noticed that one of the solution from internet is as follows ...
SKPS's user avatar
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0 answers
15 views

Python | Normalized Vector Based Player Controller

I recently started writing a 3D Engine using the Math Library, and PyGame for Graphics. I've made a simple demo scene, but I would like to make a "First-Person" like Camera Controller. I've ...
Landen Barker's user avatar
0 votes
2 answers
38 views

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,...
Becker Mammat's user avatar
0 votes
2 answers
87 views

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] ...
Lucky's user avatar
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0 votes
1 answer
133 views

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 ...
NaiveBae's user avatar
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11 votes
5 answers
3k views

Does an algorithm's space complexity include input?

Consider the Kadane's algorithm for finding maximum subarray within an array: ...
Eugene Yarmash's user avatar
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1 answer
68 views

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 ...
p200401Samuel's user avatar
1 vote
1 answer
38 views

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'\...
levav ferber tas's user avatar
1 vote
1 answer
57 views

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 & ...
Superluminal's user avatar
1 vote
1 answer
125 views

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 ...
André Carvalho's user avatar
0 votes
1 answer
120 views

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 ...
FreeMind's user avatar
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0 votes
1 answer
85 views

Design an algorithm to calculate stock prices on a given day

Given a list of lists containing tuples in sorted(by day) order find and print the total number of stock units owned for every day that occurs at least once. ...
Remixt's user avatar
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2 votes
4 answers
120 views

Algorithm that finds 4 "O"s or 4 "X"s on a diagonal, horizontal, or vertical

My algorithm homework revolves around matching 4 "O"'s or 4 "X"'s on a diagonal, horizontal, or vertical. ...
bbartling's user avatar
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1 vote
2 answers
434 views

Is the complexity of this two-sum binary search algorithm $O(\lg n)$ or $O((\lg n)^2)$?

This algorithm solves the Two-Sum problem$^1$ assuming that the input array/list is sorted. ...
joseville's user avatar
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1 vote
0 answers
38 views

Long and short memory in reinforcement learning Connect 4 AI

I'm writing an AI based on reinforcement learning to play Connect 4. That's my second bot and attempt to RNN and AI (first was copy a code of snake RNN AI from youtube) and I'm looking for some ...
Saguro's user avatar
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0 votes
1 answer
284 views

Finding a Hamiltonian Cycle in a directed graph - graph problem

$N$ towns are given, which we can get to by passing through the northern and southern gates. If you enter a town through a gate, you have to use another gate to leave the town. The merchant would like ...
PK96's user avatar
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3 votes
2 answers
745 views

Number of Inversions found in Selection sort vs Exchange sort

Exchange sort is similar to selection sort, just swaps "overly eagerly" instead of finding the minimum and doing only one swap. And the swaps affect how often the ...
Kelly Bundy's user avatar
0 votes
2 answers
1k views

Dynamic Programming - Difficult Jumping Frog Problem

Given a set of $n$ stones, arranged in a row at equal distances from each other. The stones are numbered from $0$ to $n-1$. A frog that is on stone number $0$ has to get to stone number $n-1$. A jump ...
PK96's user avatar
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-5 votes
1 answer
535 views

Implementing Flajolet–Martin algorithm in Python

I am stuck on what to do. I am trying to create a simple implementation of the Flajolet–Martin algorithm using Python. The stream will be the contents of a text file and you will produce an ...
Hill Paul's user avatar
0 votes
1 answer
226 views

Is it faster to use Counting Sort to lexicographically sort characters in a word in Python?

Assuming I have very long words, is it worth it to use Counting Sort with its memory overhead to achieve linear time complexity? I wrote a Python function that sorts the characters in a given string ...
Daniel's user avatar
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0 votes
0 answers
205 views

render = font.render(text, 1, (0, 0, 0)) pygame.error: Library not initialized

the error im receiving is : file "/home/lucas/python/cargame/utils.py", line 17, in blit_text_center render = font.render(text, 1, (0, 0, 0)) pygame.error: Library not initialized the ...
LEJP's user avatar
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3 votes
1 answer
148 views

Using pre-,post-, and in-order indexes to find information about a Binary Search Tree

Recently I have been studying ways of traversing a BST (in python), and have collided with the terms pre-order, post-order and in-order. I believe that I understood the three terms pretty well, and ...
Rodrigo's user avatar
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2 votes
2 answers
648 views

Doubt about computing running time / time complexity of a function in Python

I am learning about time complexity now, and I am working with BST (Binary Search Trees). This question needs some context and this is a follow up post to this post. Basically, I would like to compute ...
Rodrigo's user avatar
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2 votes
1 answer
64 views

Which approach of mine for an algorithm upper bound is correct?

Say we have this algorithm in Python. ...
CSch of x's user avatar
1 vote
1 answer
153 views

When to stop training a back propagation algorithm based on the MSE?

I have a fully connected neural network that consists of 3 inputs + bias, 4 neuron hidden layer, and 2 layer output, I am using the sigmoid activation function on the hidden layer only and use the ...
sfhdfh23's user avatar

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