Skip to main content

fastest way to stack ndarrays

Gist

Basically I want to perform an increase in dimension of two axes on a n-dimensonal tensor. For some reason this operation seems very slow on bigger tensors. If someone can give me a reason or better method I'd be very happy.

Goal

Going from (4, 8, 8, 4, 4, 4, 4, 4, 16, 8, 4, 4, 1) to (4, 32, 8, 4, 4, 4, 4, 4, 4, 8, 4, 4, 1) takes roughly 170 second. I'd like to improve on that. Below is an example, finding the correct indices is not necessary here.

Example Code

Increase dimension (0,2) of tensor

tensor = np.arange(16).reshape(2,2,4,1)
I = np.identity(4)

I tried 3 different methods:

np.kron

indices = [1,3,0,2]
result = np.kron(
            I, tensor.transpose(indices)
        ).transpose(np.argsort(indices))
print(result.shape) # should be (8,2,16,1)

manual stacking

col = []
for i in range(4):
    row  = [np.zeros_like(tensor)]*4
    row[i]=tensor
    col.append(a)
result = np.array(col).transpose(0,2,3,1,4,5).reshape(8,2,16,1)
print(result.shape) # should be (8,2,16,1)

np.einsum

result =np.einsum("ij, abcd -> iabjcd", I, tensor).reshape(8,2,16,1)
print(result.shape) # should be (8,2,16,1)

Results

On my machine they performed the following (on the big example with complex entries):

  1. np.einsum ~ 170s
  2. manual stacking ~ 185s
  3. np.kron ~ 580s


source https://stackoverflow.com/questions/71608259/fastest-way-to-stack-ndarrays
Labels:

Comments

Post a Comment

Popular posts from this blog

How to show number of registered users in Laravel based on usertype?

i'm trying to display data from the database in the admin dashboard i used this: <?php use Illuminate\Support\Facades\DB; $users = DB::table('users')->count(); echo $users; ?> and i have successfully get the correct data from the database but what if i want to display a specific data for example in this user table there is "usertype" that specify if the user is normal user or admin i want to user the same code above but to display a specific usertype i tried this: <?php use Illuminate\Support\Facades\DB; $users = DB::table('users')->count()->WHERE usertype =admin; echo $users; ?> but it didn't work, what am i doing wrong? source https://stackoverflow.com/questions/68199726/how-to-show-number-of-registered-users-in-laravel-based-on-usertype
Post a Comment
Read more

Why is my reports service not connecting?

I am trying to pull some data from a Postgres database using Node.js and node-postures but I can't figure out why my service isn't connecting. my routes/index.js file: const express = require('express'); const router = express.Router(); const ordersCountController = require('../controllers/ordersCountController'); const ordersController = require('../controllers/ordersController'); const weeklyReportsController = require('../controllers/weeklyReportsController'); router.get('/orders_count', ordersCountController); router.get('/orders', ordersController); router.get('/weekly_reports', weeklyReportsController); module.exports = router; My controllers/weeklyReportsController.js file: const weeklyReportsService = require('../services/weeklyReportsService'); const weeklyReportsController = async (req, res) => { try { const data = await weeklyReportsService; res.json({data}) console...
Post a Comment
Read more

How to split a rinex file if I need 24 hours data

Trying to divide rinex file using the command gfzrnx but getting this error. While doing that getting this error msg 'gfzrnx' is not recognized as an internal or external command Trying to split rinex file using the command gfzrnx. also install'gfzrnx'. my doubt is I need to run this program in 'gfzrnx' or in 'cmdprompt'. I am expecting a rinex file with 24 hrs or 1 day data.I Have 48 hrs data in RINEX format. Please help me to solve this issue. source https://stackoverflow.com/questions/75385367/how-to-split-a-rinex-file-if-i-need-24-hours-data
Post a Comment
Read more