All Questions
Tagged with python-2.x numpy
32 questions
2
votes
0
answers
142
views
Find the available squares for rooks in empty board using boolean arrays
I will describe two techniques, then the question will be how I can make an algorithm that is more efficient, if possible.
I want to find an efficient way to determine the squares where the pieces on ...
- 143
0
votes
1
answer
528
views
Image color-moment extractor [closed]
I was just wondering if there is a way to speed up the performances of this for loops in Python.
I'm trying to process an image to get the color-moments without using libraries.
It takes about 12sec ...
- 11
2
votes
0
answers
122
views
Extract cell values from multiband rasters
I have the following function and code snippet to extract cell values for multiple years, format it, and save to a list. Each raster has 365 bands — one for each day. A separate operation is performed ...
- 121
5
votes
1
answer
1k
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 ...
- 421
7
votes
1
answer
1k
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 ...
- 421
2
votes
3
answers
437
views
Code to find the sum of the product of all size-n combinations of an array
The title is a bit of a mouthful, so here's a quick example:
You've got an array, maybe just the digits 1-3, and you want to get the sum of product of all size-2 combinations of the array. Those ...
- 23
6
votes
2
answers
3k
views
Remove outliers from a point cloud
This function accepts a cloud of points, and returns those points that are within delta distance of the average (mean) position.
...
- 475
3
votes
2
answers
4k
views
Calculate True Positive, False Positive, True Negative and False negative and colourize output
Objective : Calculate True Positive, False Positive, True Negative and False negative and colourize the image accordignly, based on ground-truth and prediction from my classifier model.
Problem : ...
user108668
5
votes
1
answer
211
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Using NumPy to scale data in 2 out of 3 columns
The below code takes a csv containing age, weight, height and prints the betas determined through linear regression to an output csv. It runs for 10 iterations using a different alpha for each, and ...
- 125
5
votes
1
answer
5k
views
Applying Laplacian smoothing to vertices in a mesh
I'm totally new in Python and I wrote some code. It is a simple algorithm to smooth objects. I need to find adjacent vertices in mesh and sum their coordinates and after that divide by a number of ...
- 51
3
votes
0
answers
1k
views
Implementing the stochastic gradient descent algorithm of the softmax regression with only NumPy [closed]
I am implementing the stochastic gradient descent algorithm. I think there is plenty of room for improvement.
...
- 325
5
votes
2
answers
1k
views
A command-line utility to solve a system of linear equations
I was re-checking my answers for a Math paper on my laptop. I needed to verify my solution for a system of linear equations. Unfortunately, I found no quick way to do that. That's why I wrote a (...
- 3,017
5
votes
2
answers
849
views
Python Cartesian Product in a constrained dictonary
I want to calculate the Cartesian product of n copies of a small list, marker=[0,1,2]. I want to use these Cartesian product ...
- 245
4
votes
1
answer
335
views
Surface Density Profile
I am trying to compute the surface density profile, given the spherical density profile in 3D for different parameters in order to interpolate and have it as a function of them to use later on for ...
- 53
2
votes
1
answer
181
views
Slicing a big NumPy array
I have a function that takes a four-dimensional NumPy array M and, for each value i of its second index, takes all of M without the i-th "column", evaluates the product over all other columns, and ...
- 123
3
votes
3
answers
600
views
Creating and manipulating FITS files
I wrote a program that manipulated data from VLA observations and created FITS files to be used in creating spectral energy distributions of high redshift radio galaxies. I really tried to be as ...
- 523
9
votes
1
answer
4k
views
Optimizing a python script with large arrays
I have a python script that I'd like to speed up. I'm hoping some of the gurus here can offer some advice.
The script reads in some data from file: 2 arrays with lat/lon vals, 3 arrays with image ...
- 201
2
votes
1
answer
781
views
Benchmark using floating point math
I wrote some code in Python, to benchmark mathematical operations. It does not do anything in particular besides just calculating a lot of floating point numbers.
To clarify: I need 128-bits ...
- 43
8
votes
3
answers
2k
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 ...
- 421
6
votes
4
answers
2k
views
Kadane's Algorithm for 2D array with known boundaries
I asked this question first on StackOverflow but I didn't get an answer and was advised to try here too. So here we go.
I have implemented Kadane's algorithm for a 2D array in Python 2 with known ...
- 163
11
votes
1
answer
2k
views
Balanced Random Assignment in Python
It has been a very long time since I've used Python.
What I'm looking for: I would like to create a 6-by-6 random matrix where each component is either 1 or 2, so that there are 18 ones and 18 twos.
...
- 301
14
votes
1
answer
1k
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 ...
Mast♦
- 13.5k
3
votes
1
answer
394
views
Instantiating a kind of NumPy array
I am creating a class object which must inherit from numpy ndarrays. I perform an isinstance check and an ...
- 218
3
votes
1
answer
1k
views
Iterate over coordinates and correct constraint violations
I am creating an algorithm to take a series of labelled points placed randomly and move them until they fulfil a set of constraints.
The constraints have been pre-computed and are each a lower and ...
- 153
1
vote
2
answers
273
views
Sieve of Erathosthenes speedup
While reading HackerNews, I learned about a data set of the first 50 million primes. This would be a lot, but his website has disclaimer:
n this directory I have the first fifty million primes in ...
- 242
2
votes
1
answer
690
views
Speed up a function using NumPy
I have a function written in Python 2.7 that I call several times in a program. This function is rather slow, and I'd like to rewrite it in NumPy. However, I don't know how to do it.
I basically have ...
- 475
10
votes
1
answer
14k
views
4
votes
1
answer
200
views
Function that transforms input file based on a numpy poly1d function
I have written a function that gets a function as input (acquired from numpy.poly1d). The function has access to the GUI variables ...
- 275
3
votes
2
answers
726
views
Reduction function in Rainbow tables implementation
I'm working on an implementation of Rainbow tables as part of a project. I understand the main principles behind it had have a working solution. Unfortunately the reduction function portion of my ...
- 131
3
votes
1
answer
7k
views
Fast loop to create an array of values [closed]
I have a code that creates a 3D array of values from a minimum to a maximum in X and Z with constant Y.
Right now I make it in normal Python, and then I transform it in a ...
- 475
8
votes
2
answers
30k
views
K-means clustering in Python
The following code uses scikit-learn to carry out K-means clustering where \$K = 4\$, on an example related to wine marketing from the book DataSmart. That book uses excel but I wanted to learn Python ...
- 225
14
votes
1
answer
10k
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 ...
- 475