Concatenating two Arrays

[alv-around]

First of all thanks for the project. I think is a very cool idea, but I am struggling in with a very simple case:

Goal: I want to concatenate to FieldArrays

I have two arrays $A, B \in F_{p}^{nxn}$ and I would like to obtain $C \in F_{p}^{2nxn}$ (or $F_{p}^{nx2n}$, the axis in my case is not important).

Put it in code:

A = F([[1, 2], [3, 4]])
B = F([[5, 6], [7, 8]])
C = F([[1, 2], [3, 4], [5, 6], [7, 8]])

Failed Approaches:

I have tried a couple approaches before comming here, and all have failed:

• np.concatenate(A, B) results in the following error:

    C = np.concatenate(A, B)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alv/.local/share/virtualenvs/binius-uW3OI3G1/lib/python3.12/site-pack
ages/galois/_domains/_function.py", line 373, in __array_function__
    output = super().__array_function__(func, types, args, kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: only integer scalar arrays can be converted to a scalar index

• A.append(B)I get the following error:

     C = A.append(B)
              ^^^^^^^^^^^^
AttributeError: 'FieldArray_101_2' object has no attribute 'append'

• A + B -> The "pure" python way, which results in C being an Array of the same size as A and B and provides element-wise sum. That is totally fine and is aligned with np. I just added here to be exhaustive.

I am missing something?

If I could go out of my way, to get it work. But I also think that if the purpose of the library is to provide a seamless experience with np, scipy, ... such an elementary operation should provide a simple interface.

Solution

After a couple more trials I made it work by calling:

C = np.append(A, B, axis=0)

[mhostetter]

Is this your goal? I think np.vstack() and np.hstack() may be what you're looking for.

import galois

F = galois.GF(101)

A = F([[1, 2], [3, 4]])
B = F([[5, 6], [7, 8]])
C = np.vstack((A, B))

print(C)

[[1 2]
 [3 4]
 [5 6]
 [7 8]]

[alv-around]

yes! Thank you very much :)