sample_map.py

import matplotlib.pyplot as plt
import numpy as np

DURATION = 12
FPS = 25
START = 0
STEPS = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]


if __name__ == "__main__":
    # Generate data.
    x = []
    for i in np.arange(FPS * DURATION):
        if i < START:
            x.append(0)
        elif i == START:
            x.append(1)
        else:  # i > START:
            t = int(i / FPS)
            STEP = STEPS[t]
            if (i - START) % STEP == 0:
                x.append(1)
            else:
                x.append(0)

    x = np.reshape(x, [DURATION, FPS]).T

    # Draw the density.
    plt.spy(x, precision=0, markersize=7, markerfacecoloralt='green', origin='lower')

    # Set labels in image.
    ylabels = [str(s) for s in np.arange(1, 25) if s % 2 == 0]
    xlabels = [str(s) for s in np.arange(1, 13) if s % 2 == 0]
    plt.yticks(np.arange(1, 25, step=2), labels=ylabels)
    plt.xticks(np.arange(1, 12, step=2), labels=xlabels)

    plt.ylabel('Frame')
    plt.xlabel('Time (s)')

    # Set figure title.
    plt.title('Sampling map (3rd try)')

    # Show the result.
    plt.gca().invert_yaxis()
    plt.gca().xaxis.set_ticks_position('bottom')
    plt.savefig('sample_map_nu_s{}.png'.format(STEP),
                bbox_inches='tight', pad_inches=0.2)
    plt.show()