import matplotlib.pyplot as plt
import numpy as np

def plot_quadrants(ax, array, fixed_coord, cmap):
    """For a given 3d *array* plot a plane with *fixed_coord*, using four individual quadrants."""
    nx, ny, nz = array.shape
    index = {
        'x': (nx//2, slice(None), slice(None)),
        'y': (slice(None), ny//2, slice(None)),
        'z': (slice(None), slice(None), nz//2),
    }[fixed_coord]
    plane_data = array[index]

    n0, n1 = plane_data.shape
    quadrants = [
        plane_data[:n0//2, :n1//2],
        plane_data[:n0//2, n1//2:],
        plane_data[n0//2:, :n1//2],
        plane_data[n0//2:, n1//2:]
    ]

    min_val = array.min()
    max_val = array.max()
    
    cmap = plt.get_cmap(cmap)
    
    for i, quadrant in enumerate(quadrants):
        facecolors = cmap((quadrant - min_val) / (max_val-min_val))
        if fixed_coord == 'x':
            Y, Z = np.mgrid[0:ny//2, 0:nz//2]
            X = nx//2 * np.ones_like(Y)
            Y_offset = (i // 2) * ny//2
            Z_offset = (i % 2) * nz//2
            ax.plot_surface(X, Y + Y_offset, Z + Z_offset, rstride=1, cstride=1, facecolors=facecolors, shade=False)
        elif fixed_coord == 'y':
            X, Z = np.mgrid[0:nx//2, 0:nz//2]
            Y = ny//2 * np.ones_like(X)
            X_offset = (i // 2) * nx//2
            Z_offset = (i % 2) * nz//2
            ax.plot_surface(X + X_offset, Y, Z + Z_offset, rstride=1, cstride=1, facecolors=facecolors, shade=False)
        elif fixed_coord == 'z':
            X, Y = np.mgrid[0:nx//2, 0:ny//2]
            Z = nz//2 * np.ones_like(X)
            X_offset = (i // 2) * nx//2
            Y_offset = (i % 2) * ny//2
            ax.plot_surface(X + X_offset, Y + Y_offset, Z, rstride=1, cstride=1, facecolors=facecolors, shade=False)


def figure_3D_array_slices(array, cmap=None):
    """Plot a 3d array using three intersecting centered planes."""
    fig = plt.figure()
    ax = fig.add_subplot(projection='3d')
    ax.set_box_aspect(array.shape)
    plot_quadrants(ax, array, 'x', cmap=cmap)
    plot_quadrants(ax, array, 'y', cmap=cmap)
    plot_quadrants(ax, array, 'z', cmap=cmap)
    return fig, ax


nx, ny, nz = 70, 100, 50
r_square = (np.mgrid[-1:1:1j*nx, -1:1:1j*ny, -1:1:1j*nz]**2).sum(0)

figure_3D_array_slices(r_square, cmap='viridis_r')
plt.show()