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numpy

How to convert a PIL Image into a numpy array?

August 20, 2022 by Magenaut

Alright, I’m toying around with converting a PIL image object back and forth to a numpy array so I can do some faster pixel by pixel transformations than PIL’s PixelAccess object would allow. I’ve figured out how to place the pixel information in a useful 3D numpy array by way of:

Categories Python, Q&A Tags image, numpy, numpy-ndarray, python, python-imaging-library Leave a comment

Pandas read_csv low_memory and dtype options

August 20, 2022 by Magenaut

When calling

Categories Python, Q&A Tags dataframe, numpy, pandas, parsing, python Leave a comment

Unable to allocate array with shape and data type

August 20, 2022 by Magenaut

I’m facing an issue with allocating huge arrays in numpy on Ubuntu 18 while not facing the same issue on MacOS.

Categories Python, Q&A Tags data-science, numpy, python Leave a comment

Finding local maxima/minima with Numpy in a 1D numpy array

August 20, 2022 by Magenaut

Can you suggest a module function from numpy/scipy that can find local maxima/minima in a 1D numpy array? Obviously the simplest approach ever is to have a look at the nearest neighbours, but I would like to have an accepted solution that is part of the numpy distro.

Categories Python, Q&A Tags numpy, python Leave a comment

Saving a Numpy array as an image

August 20, 2022 by Magenaut

I have a matrix in the type of a Numpy array. How would I write it to disk it as an image? Any format works (png, jpeg, bmp…). One important constraint is that PIL is not present.

Categories Python, Q&A Tags image, numpy, python Leave a comment

Indexing one array by another in numpy

August 20, 2022 by Magenaut

Suppose I have a matrix A with some arbitrary values:

Categories Python, Q&A Tags numpy, python Leave a comment

Efficiently Using Multiple Numpy Slices for Random Image Cropping

August 20, 2022 by Magenaut

I have a 4-D numpy array, with the first dimension representing the number of images in a data set, the second and third being the (equal) width and height, and the 4th being the number of channels (3). For example let’s say I have 4 color images that are 28*28, so my image data looks like this:

Categories Python, Q&A Tags image-processing, numpy, python Leave a comment

Dump a NumPy array into a csv file

August 20, 2022 by Magenaut

Is there a way to dump a NumPy array into a CSV file? I have a 2D NumPy array and need to dump it in human-readable format.

Categories Python, Q&A Tags arrays, csv, numpy, python Leave a comment

What does axis in pandas mean?

August 20, 2022 by Magenaut

Here is my code to generate a dataframe:

Categories Python, Q&A Tags dataframe, numpy, pandas, python Leave a comment

Shared-memory objects in multiprocessing

August 20, 2022 by Magenaut

Suppose I have a large in memory numpy array, I have a function func that takes in this giant array as input (together with some other parameters). func with different parameters can be run in parallel. For example:

Categories Python, Q&A Tags multiprocessing, numpy, parallel-processing, python, shared-memory Leave a comment
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  1. michealSmith07 on Is there a way to dynamically refresh the less command?August 21, 2022

    That is a very nice post. I like this post.

  2. anonymous on Fix libwacom9 dependency issue when upgrade DebianJune 27, 2022

    saved my day!! Thanks for the help…

  3. sreedhar on Fix libwacom9 dependency issue when upgrade DebianMay 10, 2022

    Thanks its working

  4. saintnick on Fix libwacom9 dependency issue when upgrade DebianMay 10, 2022

    remove libwacom2 worked for me as well

  5. ranafoul on Fix libwacom9 dependency issue when upgrade DebianApril 22, 2022

    apt remove libwacom2 helped on kali 2022.01. gr8

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