Log24

Another cultural inflection point:

Susan Sontag,
Notes on “Camp”

This post was suggested by an Instagram ad this evening —

From April 14, 2024,  some culture notes that I prefer —

An example of pi.ai's clear and pleasant conversational style
(output format simplified for presentation here) —

Can you help with computer coding problems?
 

Absolutely, Steven! 💻 While I can't guarantee I'll have all the answers, 
I'll certainly do my best to help you debug and find solutions to your 
coding conundrums. Which coding language are you working with, and what's 
giving you trouble?

 
I want to learn how Python can permute sections of a square array.
 

There are several ways to permute sections of a square array in Python, 
depending on your specific needs. Here are a few examples:

Using NumPy's random.permutation() function:

python

    import numpy as np

    arr = np.array([[1, 2], [3, 4]])
    permuted_arr = np.random.permutation(arr)

 

    Using itertools.permutations():

python

    import itertools

    arr = [[1, 2], [3, 4]]
    permutations = list(itertools.permutations(arr))

 

Using custom permutation algorithms:

python

    def custom_permutation(arr):
        # your custom permutation logic here

    arr = [[1, 2], [3, 4]]
    permuted_arr = custom_permutation(arr)

Each method has its own strengths and weaknesses, and which one 
you choose will depend on the size of your array, the number of 
permutations you need, and your performance requirements.


I would like to use python's custom permutation method to permute 
the four quadrants of a 4×4 array.

 
Here's an example of how to define a custom permutation function 
in Python to permute the four quadrants of a 4×4 array:
 
python

    def custom_permutation(arr):
        # Split array into 4 quadrants
        q1 = arr[:2, :2]
        q2 = arr[:2, 2:]
        q3 = arr[2:, :2]
        q4 = arr[2:, 2:]

        # Permute quadrants
        permuted_arr = np.block([
            [q3, q1],
            [q4, q2]
        ])

        return permuted_arr

    # Sample 4x4 array
    arr = np.array([[1, 2, 3, 4],
                    [5, 6, 7, 8],
                    [9, 10, 11, 12],
                    [13, 14, 15, 16]])

    permuted_arr = custom_permutation(arr)
    print(permuted_arr)

In this example, we've defined a function custom_permutation() 
that takes a 4×4 NumPy array as input. The function splits the array 
into four quadrants (q1, q2, q3, and q4), and then uses NumPy's block() 
function to create a new array with the quadrants permuted. The 
resulting permuted_arr array has its quadrants rearranged.

Of course, this is just one possible permutation of the array's quadrants. 
You can modify the custom_permutation() function to implement other 
permutations as needed.
 

I tried the code you gave me and got the error “np name not defined.”
 

Apologies for that! I missed an import statement in the previous example. 
You need to import the NumPy library at the beginning of your script to 
use the np alias and its functions. Here's the corrected code:
 
python

    import numpy as np

    def custom_permutation(arr):
        # Split array into 4 quadrants
        q1 = arr[:2, :2]
        q2 = arr[:2, 2:]
        q3 = arr[2:, :2]
        q4 = arr[2:, 2:]

        # Permute quadrants
        permuted_arr = np.block([
            [q3, q1],
            [q4, q2]
        ])

        return permuted_arr

    # Sample 4x4 array
    arr = np.array([[1, 2, 3, 4],
                    [5, 6, 7, 8],
                    [9, 10, 11, 12],
                    [13, 14, 15, 16]])

    permuted_arr = custom_permutation(arr)
    print(permuted_arr)

This code should work now without any issues.

It did work. Thank you, Pi. 

You're very welcome, Steven! I'm glad the code worked for you. 
If you have any more questions or need help with anything else, 
feel free to ask.