Numpy Vectorized Function Over Successive 2d Slices

2024/11/17 16:54:10

I have a 3D numpy array. I would like to form a new 3d array by executing a function on successive 2d slices along an axis, and stacking the resulting slices together. Clearly there are many ways to do this; I'd like to do it in the most concise way possible. I'd think this would be possible with numpy.vectorize, but this seems to produce a function that iterates over every value in my array, rather than 2D slices taken by moving along the first axis.

Basically, I want code that looks something like this:

new3dmat = np.vectorize(func2dmat)(my3dmat)

And accomplishes the same thing as this:

new3dmat = np.empty_like(my3dmat)
for i in range(my3dmat.shape[0]):new3dmat[i] = func2dmat(my3dmat[i])

How can I accomplish this?

Answer

I am afraid something like below is the best compromise between conciseness and performance. apply_along_axis does not take multiple axes, unfortunately.

new3dmat = np.array([func2dmat(slice) for slice in my3dmat])

It isn't ideal in terms of extra allocations and so on, but unless .shape[0] is big relative to .size, the extra overhead should be minimal.

https://en.xdnf.cn/q/71531.html

Related Q&A

MySQL and Python Select Statement Issues

Thanks for taking the time to read this. Its going to be a long post to explain the problem. I havent been able to find an answer in all the usual sources.Problem: I am having an issue with using the …

How to pass variable in url to Django List View

I have a Django generic List View that I want to filter based on the value entered into the URL. For example, when someone enters mysite.com/defaults/41 I want the view to filter all of the values mat…

Django Select Option selected issue

I tried to follow some examples on stackoverflow for option selected in select list but still, I could not get it work.This is my code snippet<select name="topic_id" style="width:90%&…

reading tab-delimited data without header in pandas

Im having trouble using pandas to open tab-delimited data without headers.My test data (actually contains 200 lines, of which I am showing the first 10):Tag19184 CTAAC hffef 1 a 36 - chr1…

Python Try/Except with multiple except blocks

try:raise KeyError() except KeyError:print "Caught KeyError"raise Exception() except Exception:print "Caught Exception"As expected, raising Exception() on the 5th line isnt caught i…

How to install trax, jax, jaxlib on M1 Mac on macOS 12?

trax New to trax, Im trying to run it locally (macOS 12.1, Apple Silicon ARM M1 processor, 8GB RAM, Anaconda), but Im running into some issues. In an environment with python 3.8.5, I installed trax run…

How do I match a word in a text file using python?

I want to search and match a particular word in a text file.with open(wordlist.txt, r) as searchfile:for line in searchfile:if word in line:print lineThis code returns even the words that contain subst…

Unable to Delete Videos with the Youtube Data API

Cant get deleting videos to work using the Youtube Data API. Im using the Python Client Library.All of this seems straight from the docs, so Im really confused as to why its not working. Heres my fun…

LLDB Python scripting in Xcode

Ive just discovered this handy feature of LLDB that allows me to write Python scripts that have access to variables in the frame when Im on a breakpoint in LLDB. However Im having a few issues when usi…

What technologies exist to create stand alone executables for Python 3?

Other than cx_Freeze, are there any other current maintained tool suites to generate stand alone executables for Python 3k?Are there any other techniques for minimizing preinstallation requirements un…