Questions tagged [numpy]
NumPy is the fundamental package for scientific computing with the programming language Python.
86
questions with no upvoted or accepted answers
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144 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 ...
7
votes
0answers
78 views
Calculation of independence test statistic
This code (~30lines) detects independence between variables in a dataset, by using a bootstrap of a statistic. This is fully-broadcasted, but it's still long.
Reading it, or making it run, do you ...
7
votes
0answers
103 views
Numerical integration in cython
I have a set of nested functions that I need to call multiple times. I know scipy.quad is pretty fast, but I will need to call the integrator recursively and want ...
6
votes
0answers
2k views
Calculating T-Test within Large Pandas Dataframes
The below code runs a t-statistic within a large dataframe (rnadf) based on masked values from another dataframe (cnvdf_maked). ...
5
votes
0answers
2k 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 ...
5
votes
0answers
514 views
Customizable Multi-Agent Predator/Prey Simulation
I am trying to create a highly customizable "battle simulator". The default setup is a predator/prey relationship (no births); however, I am trying to create code such that it's easy to add and ...
5
votes
0answers
1k views
Plotting the Mandelbrot set at different zoom levels
I'm interested in making an animated movie of a zoom in on a part of the Mandelbrot set. My code works well for a few zooms, but upon trying to zoom in quite far, I find that the fractal becomes "...
5
votes
0answers
531 views
Calculating complex exponential numbers using OpenMP in Cython
I am trying to create a function that can either beat numexpr or perform comparably for the vectorized mathematical operation ...
5
votes
0answers
275 views
Summing 2D NumPy array by multiple labels
Each element of the array is a coordinate (x, y).
Each coordinate has two labels.
Goal:
sum the elements that have the same two labels.
How can ...
4
votes
0answers
46 views
Importer for binary datafile of PI88 Nanoindenter
As an exercise, I want to rewrite a C++ program to import measurement files (and later create excelsheets, reports ...). The measurement files split in 2 files, a binary file, and a xml-file. Because ...
4
votes
0answers
557 views
numpy 2d array anti diagonal averaging
The following piece of code averages the ante-diagonal elements of a 2d array x of size (m,n) with, for my purpose, m > n.
...
4
votes
0answers
1k views
Pandas/Numpy statistical odds ratio test
I'm looking for a faster way to do odds ratio tests on a large dataset. I have about 1200 variables (see var_col) I want to test against each other for mutual exclusion/ co-occurrence. An odds ratio ...
4
votes
0answers
2k views
Applying hysteresis to a signal
Using python 3.6. I have written this code (below) to apply hysteresis to a signal (a numpy array).
My aim was to create a function that didn't require any loop to remember the previous state of the ...
4
votes
0answers
574 views
Color image classification and labeling algorithm
I have some code I've been using to de-noise some images and then label all unique and contiguous elements. The function zoneMap() de-noises the image by picking a ...
4
votes
0answers
207 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
0answers
2k views
Reducing memory consumption for Numpy array
I'm running the following code using numpy arrays, I get a MemoryError in Ubuntu, while the same code runs on Mac OSX. (Pagination is automatically setup in Mac) This process consumes around 30 GB. ...
4
votes
0answers
512 views
Find the closest parametric values corresponding to a BSpline's control points
On a curve generated by scipy.interpolate.BSpline I want to find the closest
parameters relative to each control point, so that the given parametric range is ...
4
votes
0answers
897 views
2-D Kalman Filtering in Python using Numpy
I am practicing Kalman filtering and wrote a short python class that uses Numpy to calculate the 2-D kalman filter for position and velocity along the X axis: assume that the object is only moving ...
4
votes
0answers
3k views
Implementation of the Householder Transformation
I implemented the Householder transformation in Python, so that I can later use it in a QR decomposition. Unfortunately I haven't found a good concise source for reading up on the algorithm.
I am not ...
4
votes
0answers
199 views
Simple Stateful LSTM example with arbitrary sequence length
I'm trying to make a simple example showing how to create a RNN with Keras that accepts as input a sequence of arbitrary length. In my example, the LSTM is trying to classify whether a sequence has ...
4
votes
0answers
408 views
Plant/Residue Detection project, How to structure it?
Introduction
I have wanted to develop this project for more than two years. I just started writing it a couple days ago. I use it to detect plant or residue pixels in crop row images but it provides ...
4
votes
0answers
432 views
Python Code For Drawing a Fractal Tree using pyglet
So I've just finished doing a coding challenge that involved drawing a fractal tree. Instead of doing it recursively(which is what I did initially but it proved to be to slow for branches greater than ...
4
votes
0answers
229 views
Generalized NumPy reshape function to imitate einsum syntax
I often perform a lot of reshape(), transpose() or squeeze() operations on ...
3
votes
0answers
61 views
Clean and fast MiniMax for numpy implementation of Tic-Tac-Toe
Tic-tac-toe is small enough to be solved completely but since I have a slow computer and this is an interesting exercise, I want to build the fastest possible minimax tic-tac-toe implementation in ...
3
votes
0answers
108 views
Implementing a tic tac toe board in python
This is my attempt at making a class to represent a game board for tic tac toe. I normally hate while loops but I used one because I cant seem to make the ...
3
votes
0answers
37 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
65 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 ...
3
votes
0answers
47 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
647 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 ...
3
votes
0answers
123 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
0answers
100 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:
$$f_{D,0}(...
3
votes
0answers
60 views
Minimization problem solving and its step limits
I am trying to solve the following minimization problem:
$$
\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
...
3
votes
0answers
1k 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
0answers
76 views
Variable bit length lossy floating point compression
I am implementing a new compression algorithm for the weights of a neural network for the Leela Chess project. the weights are roughly 100Mb of ...
3
votes
0answers
84 views
Data set generation with Python and Matplotlib
I want to use Python and Matplotlib to create a data set of images. I want to do this by transforming the plot to a numpy matrix. At the moment it takes about 0.1 second to generate 100 images of size ...
3
votes
0answers
145 views
Searching for the location of a sub-image within an image
I have a number of images that were cropped and their backgrounds removed. I've tried to write a function that will search the original unmodified image for the cropped image so that I can restore the ...
3
votes
0answers
152 views
Merging bin-data via a bin count threshold
When performing a chi-squared test, one takes the square of the differences of the expected counts per bin and observed counts per bin, and divides these per-bin differences by the expected counts per ...
3
votes
0answers
68 views
Numpy versus Theano GPU parallelization
I am learning Theano to accelerate my image processing functions. As a start, I am trying to reimplement the function to turn images from colors to black and white (with the same number of channels): ...
3
votes
0answers
42 views
Deriving incremental feature representations for bit flips
Given a boolean 3D matrix and a set of actions specifying bit flips at certain positions, a set of resulting matrices can be obtained, one matrix for each action, as if executing each bit flip ...
3
votes
0answers
3k views
Reading a csv file and making a histogram in Python using NumPy and Matplotlib
I have written the following code which reads a csv file that contains a bunch of words and their sentiment value. Words like abandon may have a value of -1, while words like progress and freedom have ...
3
votes
0answers
308 views
Applying Scikit-Learn Linear Kernel with a generator for low memory pressure
matrix = # a sparse matrix of TFIDF vectors - 28458x3218988
My aim was to create a similarity matrix comparing all documents to all documents using ...
3
votes
0answers
459 views
pandas time-based qcut
I have a dataframe pairs where each row is a transaction with corresponding price and date. Now, I need to assign each transaction to a quintile (add a new column), ...
3
votes
0answers
139 views
Simple finite difference employing Maccormack technique
I am relatively new to programming and while I am fairly comfortable with the math, I cannot say with confidence that I feel the same way with programming. Anyway here is a simple finite difference ...
3
votes
0answers
136 views
Speed up a Gibbs sampler with Cython
I have implemented a Gibbs sampler to generate textured images. According to the beta parameters (array of shape(4)), we can generate various textures.
Here is my ...
3
votes
0answers
374 views
Cythonized version of FDCT (fast discrete cosine transform) function, ported from Java
This is my Cython code for an FDCT function (invoked here):
...
2
votes
0answers
24 views
Profiling for Bézier curve calculations
Recently I posted an answer on a question about Bézier curve calculations. As a micro-synopsis: there are three implementations of De Casteljau's algorithm here, including the original poster's, AJ ...
2
votes
0answers
35 views
Convoluting 3D image with 2D
I have a single image of shape img.shape = (500, 439, 3)
The convolution function is
...
2
votes
0answers
45 views
Generate Black and White confidence map masks for joints, same as OpenPose/Convolutional Pose Machines
Attached below is my code for generating the confidence maps for the joint locations, it is in the same vein as the maps generated for the paper Convolutional Pose Machines and OpenPose. I am ...
2
votes
0answers
54 views
Python - How to efficiently bin multiple dependent variables to a common independent variable?
Setup: I have ~30 parameters (dependent variables) measured simultaneously along a common time axis with ~1Hz resolution (independent variable). I need to calculate bin averages for all parameters, ...
2
votes
0answers
59 views
Python list operation - merge adjacent cubes into minimum number of shapes
I am hoping to find a way to make the process a lot faster. The lists are made of rows of 6 numbers, i.e. [[float] * 6, ...]. The intent is to pass a list of cube ...
