Find matching rows in a numpy matrix of 3

Question

Given a cube of mxmxm, I need to know the rows, in the 6 faces that the smallest value in their row is greater than a given n.

Answer 1

To obtain the various faces:

faces = np.array([
    x[ 0,  :,  :],
    x[-1,  :,  :],
    x[ :,  0,  :],
    x[ :, -1,  :],
    x[ :,  :,  0],
    x[ :,  :, -1],
])

Now collapse the last dimension axis:

# No information on orientation provided by OP so always pick axis=-1
row_mins = np.min(faces, axis=-1)

And then keep only the rows that satisfy the condition:

valid_rows = faces[row_mins > n]
print(valid_rows)