How to plot series of images onto a particular map

Question

I wanted to plot images in a particular pattern as shown in the image below

I wanted to understand what would be the best way to plot images using python. I used the following method in which plots images in a grid pattern. output looks like this

import numpy as np
import matplotlib.pyplot as plt
from datetime import datetime
import matplotlib as mpl
from matplotlib.dates import date2num
import matplotlib.dates as mdates
from mpl_toolkits.axes_grid1 import ImageGrid

img0 = f['B00'][i_ant, :, :]
img1 = f['B01'][i_ant, :, :]
img2 = f['B02'][i_ant, :, :]
img3 = f['B03'][i_ant, :, :]
    

img_arr = [img0,img1,img2,img3]
fig = plt.figure(figsize=(5., 5.))
grid = ImageGrid(fig, 111, 
                     nrows_ncols=(2, 2),  # creates 2x2 grid of axes
                     axes_pad=0,  # pad between axes
                     )

for ax, im in zip(grid, img_arr):
    ax.imshow(im)
        

plt.show()

Answer 1

For each additional level of the square spiral, two sides are added, except for the very last one where only one side is needed. The i,j positions increment or decrement with 1 at every step, and at each corner the direction is turned 90 degrees.

This is how it could work:

import matplotlib.pyplot as plt
import numpy as np

N = 6
fig = plt.figure(figsize=(16, 18), constrained_layout=True)
spec = fig.add_gridspec(ncols=N * 2 - 1, nrows=N * 2 - 1)
i, j = N - 2 + N % 2, N - 1
dir_i, dir_j = 1, - 1
plot_num = 0
for k in range(1, N + 1):
    for _ in range(2):  # add two strokes of k subplots (only 1 when k==N)
        for _ in range(k):
            ax = fig.add_subplot(spec[i, j])
            ax.imshow(np.random.rand(3, 3))
            ax.set_xlabel(f'{plot_num} [{k}]', fontsize=18)
            plot_num += 1
            i += dir_i
            j += dir_j
        if k == N:
            break
        dir_i, dir_j = -dir_j, dir_i
plt.show()

To copy the original numbering exactly, some concentric squares can be drawn. For odd N, the last square is quite irregular, with only 2 sides, where the last line jumps to the opposite side and with one square less than the rest.

For the weird numbering of 2 and 3, some renumbering can be introced:

import matplotlib.pyplot as plt
import numpy as np

N = 6
fig = plt.figure(figsize=(16, 18), constrained_layout=True)
spec = fig.add_gridspec(ncols=2 * N - 1, nrows=2 * N - 1)
plot_num = 0
for k in range(2, N + 2, 2):
    # i, j = N - 2 + N % 2, N - 1
    i, j = N - k + N % 2, N - 1
    dir_i, dir_j = 1, - 1
    for side in range(4):  # add four strokes of k subplots (only 2 when k==N)
        for _ in range(k - 1):
            ax = fig.add_subplot(spec[i, j])
            modified_plot_num = 5 - plot_num if plot_num in (2, 3) else plot_num
            ax.imshow(np.random.rand(6, 6), cmap='inferno')
            ax.set_xlabel(f'{modified_plot_num} [{k}]', fontsize=18)
            plot_num += 1
            i += dir_i
            j += dir_j
            if plot_num == N * N:  # for odd N, the very last cell should be skipped
                break
        if k == N + 1:
            if side == 0:  # for last side of uneven square: jump to the other side
                dir_i, dir_j = -dir_i, -dir_j
                i, j = i - 1, 2 * N - 2
            elif side == 1:
                break
        dir_i, dir_j = -dir_j, dir_i
plt.show()