What is best practice for accessing two dimensional numpy arrays-CodePudding

I'm a relatively new programmer and I was just wondering the best practice for accessing a certain row and column. From what I know both below work.

    array[r,c]
    array[r][c]

However, I've read that array[r,c] is better practice in general. Could someone tell me if I am correct and if so why as well as how it applies to higher-dimension arrays? Thank you so much for helping out a newcomer!

CodePudding user response：

tl;dr: array[r,c] is faster than array[r][c]

Let compare the performance of two methods. I prepared a 2D array as follow:

import numpy as np

array = np.random.rand(1000, 1000)

Then I compared the speed of two methods:

%timeit array[42, 42]

The output is:

221 ns ± 7.86 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

and for the other method:

%timeit array[42][42]

Output:

436 ns ± 8.28 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

It is obvious array[r,c] is faster than array[r][c]. I think that is because in the array[r][c] approach, first array[r] will be calculated and returned. For the sake of argument, call this result row=array[r]. Then once again, row[c] will be calculated and returned.