All Questions
39 questions
17
votes
1
answer
516
views
Efficiently selecting spatially distributed weighted points
Background:
Motivation behind writing the following code is originated in the area of computer vision. More specifically – image rectification. In order to obtain rectified images, one has to find a ...
- 1,977
13
votes
5
answers
2k
views
Iterate through two arrays calculating a statistic from indexes of zeros
I write a function which takes as input 2 arrays of zeros and ones ~8000 elements per array. Input array size is variable, can have much higher number of elements. The density of ones is expected to ...
- 182
11
votes
2
answers
9k
views
Calculating the joint probability of n events from a sample sequence of occurrences
I'm writing an algorithm to take in a sample list of sequences of events, calculate 1-step transitional probabilities from the sequences, forward or in reverse, then calculate the joint probability of ...
- 213
10
votes
1
answer
14k
views
9
votes
1
answer
16k
views
Groupby in NumPy
To avoid the XY problem, here is an example of what I need. Given the sorted integer input array
[1 1 1 2 2 3], I would like to produce the following slices, ...
- 307
8
votes
1
answer
343
views
Implementation of a new algorithm for sklearn
In the Python library, sklearn is implemented the algorithm for SparsePCA.
I have written the code for a another version of this algorithm that is much faster in some situations. I have not enough ...
- 181
7
votes
1
answer
8k
views
Python Octree Implementation
I'm working with 3D point clouds stored in Numpy arrays. I'd succesfully used the scipy's KDTree implementation for task like k-neighbors search and outlier filtering.
However I wanted to try the ...
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
6
votes
1
answer
196
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?
...
- 61
6
votes
1
answer
26k
views
6
votes
1
answer
591
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 ...
6
votes
2
answers
2k
views
Finding the best matching block/patch in Python
I wish to locate the closest matching NxN block within a WxW window centred at location (x,y) of a larger 2D array. The code below works fine but is very slow for my needs as I need to run this ...
- 61
6
votes
1
answer
944
views
Choosing evenly distributed points from a million points on a sphere
I have \$10^5\$ to \$10^6\$ points on a sphere, and want to choose some points from them which are as close as uniformly distributed as possible. For that reason, I do the following: at each step I ...
- 309
6
votes
1
answer
4k
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.
...
6
votes
1
answer
2k
views
Implementing the CutHill-McKee Algorithm
I am very much interested in the Reverse Cuthil McKee Algorithm. I have seen Fortran and C or C++ implementations of it, and I decided that it would be a nice exercise to implement it in Python.
I ...
- 497