Questions tagged [numpy]
NumPy is the fundamental package for scientific computing with the programming language Python.
41
questions
17
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1answer
4k views
Plot timings for a range of inputs
When writing Code Review answers, it becomes often necessary to measure how long the modified code takes vs how long the OP's code takes. I needed a nice way to visualize this as a function of the ...
10
votes
1answer
14k views
13
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1answer
8k views
Faster computation of barycentric coordinates for many points
I'm just starting to understand the Python syntax and I created a module that does what I wanted, but really slow.
Here are the stats of cProfile, top 10 ordered by ...
14
votes
1answer
678 views
Racetrack plotter
My Racetrack is just that. A Racetrack. You can't race it (yet) because I had trouble with collision detection, but I wanted to share it anyway.
It creates a base polygon by using ...
6
votes
2answers
5k views
Python / Numpy running 15x slower than MATLAB - am I using Numpy effeciently?
Here is some code I wrote in Python / Numpy that I pretty much directly translated from MATLAB code. When I run the code in MATLAB on my machine, it takes roughly 17 seconds. When I run the code in ...
10
votes
1answer
4k views
Game of Life with NumPy
I started this exercise with NumPy with a goal to find neighbors and return the new matrix. I want to get your feedback. Here's an example from this website. It looks like it's \$O(N^2)\$, and I'm ...
4
votes
1answer
76 views
Back to Basics - Tic Tac Toe
I've seen a few TTT related posts recently, and thought I might learn something or be reminded of certain techniques from attempting my own rendition. Here is that attempt! Hopefully any new coders ...
47
votes
3answers
117k views
Finding the closest point to a list of points
I'm trying to find the closest point (Euclidean distance) from a user-inputted point to a list of 50,000 points that I have. Note that the list of points changes all the time. and the closest distance ...
10
votes
2answers
14k views
Generating a 3D Point Cloud
I'm trying to produce a 3D point cloud from a depth image and some camera intrinsics. The image is 640x480, and is a NumPy array of bytes. The output is a (rows * columns) x 3 array of points.
I've ...
15
votes
1answer
458 views
Warhammer: How many of my attacks will succeed?
Me and a couple of mates sometimes play a game called Warhammer.
When playing the game you have options of what each model attacks.
This can lead to situations where you know if you shoot with 100% of ...
13
votes
1answer
1k views
Plotting polynomials roots
NOTE: See follow up to this question here
I created a simple python script to plot quadratic, cubic and quartic polynomials with integer coefficients between -4 and 4. It uses numpy to find the roots ...
8
votes
1answer
3k views
Remove pixel patch in image which is stored as array
I have an array I which stores N images of size P (number of pixels). Every image is of size ...
5
votes
1answer
682 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 ...
13
votes
1answer
767 views
A big “Game of Life”
Our quest: Create a big simulation for Conway's Game of Life, and record the entire simulation history.
Current Approach: Cython is used for an iterate method. The ...
7
votes
2answers
7k views
Python, numpy, optimize module to handle big file
With the help of some people here and there, I wrote the module below which works very well if the file targets.csv is not too big.
As soon as this file exceeds ...
5
votes
1answer
944 views
Hints to make Sudoku solver more Pythonic
As you will see, I am not very familiar with Python and NumPy but want to learn it.
The following code is a very basic Sudoku solver which works fine for simple examples. Although it runs, I still ...
2
votes
2answers
4k views
Simulation of 2D elastic balls
Following this SO post and this Wikipedia article, I wrote a Python script to simulate physics of 2D elastic balls.
I define the physical behaviour of each ball in the ...
13
votes
1answer
286 views
Population dynamic simulation on biological information maintenance 2
This question is the follow-up to this previous question.
Background
Using this simulation I investigate a system in which enzymes proliferate in cells. During the replications of enzymes, ...
12
votes
1answer
1k views
Python program that draws the Mandelbrot set fractal
I wrote a Python program that draws the Mandelbrot set fractal. However, the program is very slow. I would appreciate any feedback on the program, but I would especially appreciate feedback on how to ...
10
votes
1answer
31k views
Efficient numpy cosine distance calculation
I want to calculate the nearest cosine neighbors of a vector using the rows of a matrix, and have been testing the performance of a few Python functions for doing this.
...
9
votes
1answer
173 views
Population dynamic simulation on biological information maintenance
Background
Using this simulation I investigate a system in which enzymes proliferate in cells. During the replications of enzymes, parasites can come to be due to mutation. They can drive the system ...
8
votes
3answers
1k views
Python differential analysis of heat loss across a pipe
I made a differential equation solver to forecast heat loss through a pipe with heat loss coefficient contours. It does what I want it to do but I had to use global variables to change the outputs of ...
7
votes
1answer
12k views
“Histogram of Oriented Gradients” (HOG) feature detector for computer vision
Here is a function that I've only slightly modified from its original context, found here.
Before mentioning anything else, it should be noted that I'm desperately trying to optimize this code for ...
7
votes
0answers
149 views
Multithreaded HD Image Processing + Logistic reg. Classifier + Visualization
[I'm awaiting suggestions for improvement/optimization/more speed/general feedback ...]
This code takes a label and a folder path of subfolders as input that have certain labels ex: trees, cats with ...
5
votes
1answer
183 views
process numerical input arguments of mixed ints, floats, and “array-like” things of same length>1
I'm trying to process numerical input arguments for a function. Users can mix ints, floats, and "array-like" things of ints and float, as long as they are all length=1 or the same length>1.
Now I ...
4
votes
3answers
344 views
Estimating the number of tanks based on a sample of serial numbers 2.0
There was some confusion with the code I had posted in my previous version of this question and there was some good advice from @Oscar Smith.
The explanation is the same; please give improvements for ...
4
votes
2answers
5k views
Calculating if a point is within a polygon, or outside of it
Here is the function (along with its support functions):
...
4
votes
0answers
208 views
Finding where column slices of elements in multi-dimensional array are equal
Skippable Intro:
I have a dataset that corresponds to an observed time-series. The dataset is organized into a dictionary - which contains an array of years, an array of months, an array of days, an ...
4
votes
2answers
185 views
Temporal kernel filtering on video frames coming in a loop
I have a video which I read in a loop frame by frame. For every frame, I want to do temporal kernel filtering, the coefficients of which come from the input variable model (a dictionary). The temporal ...
7
votes
1answer
105 views
Weighted phase Laplacian formula
We have the following equation (weighted phase Laplacian):
\$c_{i,j} = U(i,j)\Delta^{^x}_{i,j} - U(i-l, j)\Delta^{x}_{i-1,j} + V(i,j)\Delta^{y}_{i,j} - V(i,j-1)\Delta^{y}_{i,j-1}\$
Where
\$U(i,j) = ...
6
votes
1answer
344 views
Schelling's model of Segregation Python implementation with Geopandas
If you don't know what is Schelling's model of segregation, you can read it here.
The Schelling model of segregation is an agent-based model that illustrates how individual tendencies regarding ...
6
votes
1answer
904 views
Python! (Snake)
This is now an Iterative Review.
Next Iteration
Nowhere near a full game yet. Just a basic overview and initialisation of a Snake() class.
Thoughts?
...
6
votes
1answer
2k views
Koch snowflake in Python with numpy and pygame
I've drawn a Koch snowflake with Python 3. I'm new to the Python world and would appreciate all feedback on how to make the code more Pythonic as I'm not used to these idioms, styles and modules. All ...
5
votes
1answer
1k views
Reading a binary file containing periodic samples
I have the following code for reading HTK feature files. The code below is working completely correct (verified it with unit tests and the output of the original HTK toolkit).
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4
votes
2answers
970 views
Simple one-hot encoder
Because neither sklearn nor Pandas provide a straightforward and complete one-hot encoder, I decided to write one myself. Both Pandas and sklearn do have an encoder with no option to decode, and the <...
4
votes
2answers
75 views
Creating nxm index list of array a
Here is the problem:
Given a numpy array 'a' that contains n elements, denote by b the set
of its unique values in ascending order, denote by m the size of
array b. You need to create a numpy array ...
3
votes
1answer
99 views
Getting angle between all points in array
I have got some code that calculates the angle between all of the points in an array. It works, but it is quite slow. This is because it has complexity O(n^2). It has to loop through the array and ...
2
votes
2answers
2k views
Rolling loop with an array of data points
I have a NumPy array of about 2500 data points. This function is called on a rolling basis where 363 data points is passed at a time.
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2
votes
1answer
160 views
Simple utility/convenience module - am I doing it right?
I have a large library (four packages) of data processing code that I have written over the last 12 months. I am quite new to python and would like to see if I am doing things correctly.
This utility/...
1
vote
1answer
2k views
Data cleaning - am I using classes correctly here?
I have a data processing application that does some data cleaning as the first step. This is the module I import for that purpose.
The only 'public' part of the api is the 'clean' function which ...
1
vote
0answers
61 views
Improving code for image manipulation
I'm fairly new to coding and am developing a set of functions to allow mammologists to progrmatically collect data from photos of specimens. The special issue with mammals is that their coats are ...
