How to create an updatable heatmap in Python using matplotlib?

Question

I am new to using many data visualization libraries in Python, and I am trying to create an series of methods that can create a "zeroed" 7x7 heatmap that will remain indefinitely open until a 7x7 matrix is given to it, at which point the figure will update without having to close the figure. This update would also remain open and unchanging indefinitely until another 7x7 matrix is given or the figure is closed.

Note that the reason why the program is being structured as a series of functions is so that the figure can be opened and updated from another program file. So, assuming this is possible, how can this be done?

Below is my current code:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.colors import LinearSegmentedColormap
from matplotlib.animation import FuncAnimation

def open(threshold):
    matrix = np.zeros((7,7))

    #colors = [(0, 0, 0.5), (0, 0, 1), (1, 1, 1)]
    colors_rev = [(0, 0, 0), (0, 0.5, 0), (0, 1, 0)]
    n_bins = 100
    cmap_name = "custom_green"
    cmap = LinearSegmentedColormap.from_list(cmap_name, colors_rev, N=n_bins)

    x_axis = [45, 30, 15, 0, -15, -30, -45]
    y_axis = [45, 30, 15, 0, -15, -30, -45]

    fig, axis = plt.subplots()

    heatmap = axis.matshow(matrix, cmap=cmap, vmin=threshold, vmax=1)

    # Add text annotations to each cell
    for i in range(7):
        for j in range(7):
            value = matrix[i][j]
            axis.text(j, i, f'{value:.2f}', ha='center', va='center', color='white', fontsize=8)

    axis.tick_params(top=False, labeltop=False, bottom=True, labelbottom=True)
    axis.set_xticks(np.arange(0, 7, 1))
    axis.set_yticks(np.arange(0, 7, 1))
    axis.set_xticklabels(x_axis)
    axis.set_yticklabels(y_axis)
    axis.set_xlabel('Azimuth (degrees)', fontsize=13)
    axis.set_ylabel('Elevation (degrees)', fontsize=13)

    cbar = fig.colorbar(heatmap)

    cbar.set_label('Confidence Relative to Threshold', fontsize=13)

    plt.title('Angular Position of UAS Relative to Microphone Array', fontsize=13)
    plt.show()

    return fig, axis, heatmap

def update(matrix, fig, axis, heatmap):
    pass

if __name__ == '__main__':
    #matrix = np.random.rand(7, 7)
    #print(matrix)

    test_matrix = [[0.4  , 0.3  , 0.1  , 0.131, 0.31, 0.56 , 0.123],
                   [0.3  , 0.71 , 0.79 , 0.85 , 0.74, 0.324, 0.1  ],
                   [0.1  , 0.79 , 0.95 , 0.85 , 0.42, 0.134, 0.234],
                   [0.12 , 0.83 , 0.80 , 0.79 , 0.13, 0.242, 0.234],
                   [0.23 , 0.234, 0.235, 0.234, 0.79, 0.235, 0.23 ],
                   [0.234, 0.21 , 0.12 , 0.52 , 0.13, 0.5  , 0.3  ],
                   [0.51 , 0.13 , 0.55 , 0.121, 0.12, 0.45 , 0.12 ]]

    threshold = 0.75
    fig, axis, heatmap = open(threshold)
    #update(matrix, fig, axis, heatmap)

From this code, the initial matrix in open() should create the zeroed heatmap as follows: Zeroed heatmap

The test_matrix should create the following heatmap: Heatmap with test_matrix as data input

Both work when on their own, but the transition between them is nonexistent.

I am not very familiar with pyplot to begin with, so it's difficult for me to find any solutions easily. But, I have tried a few. For one, I tried set_array followed by plt.draw() within the update() defintion, but this only led to the creation of a blank figure. Plus, the zeroed figure had to closed anyway to get that blank figure, which already failed one of my requirements.

I also tried looking into FuncAnimation, but I didn't get too far as it seemed that the animations had to be finite, with a set number of frames and such. Though, of course, I have very little understanding of FuncAnimation to begin with.

Hopefully, this question and my requirements make sense, even if they may be rather basic.