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Questions tagged [numpy]

NumPy is the fundamental package for scientific computing with the programming language Python.

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5
votes
2answers
235 views

Improve Performance of Comparing two Numpy Arrays

I had a code challenge for a class I'm taking that built a NN algorithm. I got it to work but I used really basic methods for solving it. There are two 1D NP Arrays that have values 0-2 in them, ...
6
votes
1answer
132 views

Longest carbon chain

My Code measures the longest path, not allowing cycles. For the example input below, the longest chain would be 4 Please can you review my code? ...
8
votes
1answer
221 views

Deep Neural Net implementation in Python3

I created my first implementation of an arbitrary feed forward neural network with a simple back-propagation training implementation. ...
6
votes
0answers
4k views

Cubic spline interpolation in Python from scratch

I implemented the cubic spline interpolation explained in https://en.wikipedia.org/wiki/Spline_interpolation as a Python class. Of course, such an interpolation should exist already in some Python ...
3
votes
0answers
56 views

TensorFlow regressor to predict probability of winning, given a current score

This is a TensorFlow regressor that tells me that if you get x score, you will have x% to win a game in x game(game is not important). Doing this as a project to learn tensorflow. ...
3
votes
0answers
245 views

N-D Kalman Filter in Python + Numpy

Just implemented this Kalman Filter in Python + Numpy keeping the Wikipedia notation It's a pretty straightforward implementation of the original algorithm, the goals were develop skills related to ...
6
votes
1answer
391 views

Searching extreme points of polyhedron

In my Uni, my scientific professor asked me to make some researches about the extreme points of polyhedrals. And I did them. I found that there is still no code in public for searching extreme points ...
3
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1answer
616 views

Aggregate Pandas Columns on Geospacial Distance

I have a dataframe that has 3 columns, Latitude, Longitude and Median_Income. I need to get the average median income for all points within x km of the original point into a 4th column. I need to do ...
12
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1answer
1k views

Factorio analysis: data munging

This project is... a little ridiculous. It's working, but it's a complete mess. Data about Factorio's game economy are pulled from the wiki via the MediaWiki API, scrubbed, preprocessed, and thrown ...
3
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0answers
54 views

Compare every combination of variables within the powerset

I have some survey data that represents individual's responses to multiple survey questions. There are about 10,000 people in my actual dataset, and each person answered 35 questions. From these 35 ...
3
votes
0answers
1k views

Local maxima 3D array python

I'm trying to find the local maxima in a 3D numpy array, but I can't seem to find an easy way to do that using numpy, scipy, or anything else. For now I implemented it using ...
2
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1answer
30 views

Function figuring out which close-by value comes from which input value

I would like to optimize the below traceback function. This function is part of an elementary step of the program and is called a lot... ...
6
votes
1answer
111 views

Monte Carlo errors estimation routine

I would value your opinion on the following piece of code. I am rather new to both Python and Monte Carlo analysis, so I was wondering whether the routine makes sense to more experienced and ...
5
votes
1answer
719 views

Improving the speed of creation for three Perlin Noise Maps in Python?

I am interested in learning how I can improve the speed of the code in this pygame file. I iterate over 6400 * 1800 * 3 or 34,560,000 elements of various numpy arrays here to apply noise values to ...
1
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0answers
221 views

Reduce memory consumption of numpy function

I have a Numpy function that takes the values of an existing array X and a size (int) k equivalent to the columns of the array. ...
8
votes
1answer
77 views

Python implementation of approximating the chance a particle is at a location after n steps in the cardinal directions

Recently, I became very interested in a probability practice problem in my textbook for my class. I decided to implement it in code and I think I got most of it implemented. Right now, I'm hoping to ...
7
votes
1answer
430 views

Plotting terrain pixels with PyGame based on random NumPy array

I am experimenting with Perlin Noise and random map generation. I have a 2D numpy ndarray full of 16-bit floats called map_list that I call from the singleton ...
7
votes
1answer
95 views

Extract principal components

First, I am aware that this can be done in sklearn - I'm intentionally trying to do it myself. I am trying to extract the eigenvectors from np.linalg.eig to form ...
2
votes
1answer
46 views

Calculating the potential of a matrix of size (424600, 55)

I have the following working code to calculate the potential of a matrix after normalizing the matrix. But it is too much time consuming. Is there a way to make this code run faster? ...
2
votes
1answer
69 views

Retrieval of the corners of a mask

I have trained a polygon detector neural network to recognize the mask of "quadrilateral" (the mask generates curvy lines so it's not exactly a quadrilateral). I would like to get the corners of the ...
1
vote
1answer
299 views

Vectorized N-Dimensional Random Walk in Cartesian Coordinates

I have written a random-walk routine that I hope to build upon in the future. Before doing so, I was hoping to get some critique. I believe the implementation is correct. I noticed that many other ...
2
votes
1answer
2k views

Inverse mapping with bilinear interpolation on an image

The following is my solution for an inverse mapping with bilinear interpolation on an image. The original image is img and ...
5
votes
1answer
106 views

Code to plot graphs with multiple panels efficiently

I quite often plot graphs looking at how some property or function varies with different parameters. Normally, I find the analysis code can be written fairly succinctly and separated into a suitable ...
3
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0answers
263 views

Locality Sensitive Hash (similar to k-Nearest Neighbor), in Python+Numpy

I've tried implementing Locality Sensitive Hash, the algorithm that helps recommendation engines, and powers apps like Shazzam that can identify songs you heard at restaurants. LSH is supposed to run ...
3
votes
1answer
1k views

Image pre-processing and segmentation

I'm new learning python and image processing with python. For this reason, I took a project called "Classification of breast cancer images with deep learning". I applied the following techniques: 1)...
3
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0answers
123 views

Computing Doppler delay on a meshgrid

Objective Plot the contour of the iso-doppler and iso-delay lines for a transmitter-receiver reflection on a specular plane. Implementation This Doppler shift can be expressed as follows: $$f_{D,0}(...
1
vote
1answer
163 views

Plot a piecewise-defined function

I would like to plot the following function: $$ \begin{align} \Lambda(\delta\tau) &\equiv\ \chi(\delta\tau, 0) = \frac{1}{T_i} \int_0^{T_i} a(t_0+t')a(t_0+t'+\delta\tau) dt' \\ &= \begin{...
6
votes
1answer
70 views

Optimal algorithm to move a a rope from one position to another

I'm an engineer working with a deformable membrane that is attached to actuators. The goal is to move the membrane from one shape to another, without ripping the membrane. This imposes "neighbor ...
4
votes
1answer
84 views

Set of one-hot encoders in Python

In the absence of feature-complete and easy-to-use one-hot encoders in the Python ecosystem I've made a set of my own. This is intended to be a small library, so I want to make sure it's as clear and ...
3
votes
0answers
62 views

Minimization problem solving and its step limits

I am trying to solve the following minimization problem: $$ \min\lvert\lvert{x}\rvert\rvert_1 + \beta\lvert\lvert{x}\rvert\rvert^2_2 s.t. \sum_{m = 1}^M (y - \lvert{c}^{H} . x\rvert^2)^2 \le \epsilon ...
2
votes
2answers
53 views

Compare an array with a file and form groups from elements of an array

I have a text file with letters (tab delimited), and a numpy array (obj) with a few letters (single row). The text file has rows with different numbers of columns. ...
4
votes
1answer
352 views

Fast distance calculation for Starcraft2 bot

I am coding a bot for Starcraft 2, in which many distances have to be calculated every frame. Here is the part of the library that is being used and I want to improve: https://github.com/Dentosal/...
15
votes
3answers
2k views

Generating Julia set

So, I just wanted to post something on Rosetta Code, and I found this task of generating and plotting a Julia set: http://www.rosettacode.org/wiki/Julia_set. There was already one solution but it was ...
8
votes
1answer
222 views

Cumulative sum of the smallest neighbors in the previous row in a Numpy array

I have the following code snippet, which essentially does the following: Given a 2d numpy array, arr, compute sum_arr as follow:...
9
votes
2answers
5k views

Calculating time deltas between rows in a Pandas dataframe

I am trying to compute the difference in timestamps and make a delta time column in a Pandas dataframe. This is the code I am currently using: ...
4
votes
1answer
438 views

Python script for to evaluate business data

The following script is part of a further education I'm currently enrolled into. Not all of the code is written by myself. Function signatures for example. Therefore I have put the sections, written ...
4
votes
0answers
2k views

Distance transform on image using NumPy

I would like to find the find the distance transform of a binary image in the fastest way possible without using the scipy function distance_transform_edt(). The ...
3
votes
2answers
103 views

Simulation of an alien population

Background I've come across a puzzle (Problem 10 from this list of sample interview questions): One day, an alien comes to Earth. Every day, each alien does one of four things, each with equal ...
3
votes
1answer
188 views

Dice sums comparison probability

I was playing a fun little board game called U.S. Patent No. 1 about time traveling to register your time machine as the first U.S. patent. I started to wonder what the dice probabilities were for ...
4
votes
1answer
168 views

Project structure for a reactor model built in Python

I use Python for various computational reactor modeling activities. While there are many components to the models I develop, the basic structure of the project folder tends to be similar to the ...
2
votes
0answers
88 views

Calculate average round cell value from each 2D array cell

I am try to practice the leetcode and hit the following question 'image smooth'. Basically the question is to calculate average the around cell value from a 2D array. I have following code. But if ...
3
votes
1answer
310 views

List of word to list of index in a vocabulary [closed]

I have a dataset composed of ~700k samples. Each sample is composed of n_features features. Each feature is a word. Each feature has his own vocabulary. The size of the vocabularies range from 18 to ...
1
vote
1answer
96 views

Generate xyz coordinates of a tube made of multiple rings

In this code, I generate the coordinates of a tube made of multiple rings. Finally, I write those x,y,z coordinates in a .csv file. I want to simplify this code (maybe using a for loop?). ...
1
vote
0answers
90 views

Batch gradient descent and stochastic gradient descent

I'm trying to implement logistic regression and I believe my batch gradient descent is correct or at least it works well enough to give me decent accuracy for the dataset I'm using. When I use ...
2
votes
1answer
593 views

Implementation of a threshold detection function in Python

I want to implement following trigger function in Python: Input: time vector t [n dimensional numpy vector] data vector y [n dimensional numpy vector] (values correspond to t vector) threshold tr [...
1
vote
0answers
84 views

Get stacked game state in NHWC format

After reading this, I decided to transition my DQN code from the keras library to tf.keras library (code is located in this repo) and my original code used NCHW format, as it was faster with GPUs. As ...
6
votes
1answer
3k views

Rotating an Image using own algorithm in python

For an uni assignment I have been giving the task of making my own rotating algorithm in python. This is my code so far. ...
3
votes
2answers
901 views

Stroke Algorithm in python

Here is my next Numpy practice, I am not sure is it more accurate to call it "Stroke Algorithm" or "Draw edge stuff", xD. Anyway I did in steps: calculate each pixel's RGB absolute distance to ...
3
votes
1answer
8k views

Simplex method (linear programming) implementation

The up-to-date code, along some documentation, can be found here. We've implemented a version of the Simplex method for solving linear programming problems. The concerns I have are with the design we ...
1
vote
0answers
40 views

Converting 2D arrays into strings

I have this function which converts a couple of 2D NumPy arrays into strings and then saves them in a text file (grid, quality, <...

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