import matplotlib.pyplot as plt
import numpy as np

if __name__ == "__main__":
    # wikipedia:
    # Generally, males vary in total length from 250 to 390 cm and
    # weigh between 90 and 306 kg
    c = 6
    x = np.arange(2.2, 3.9, 0.05)
    y = c * x**3.0
    rng = np.random.RandomState(32281)
    noise = rng.randn(len(x))*50
    y += noise
    
    plt.xkcd()
    fig, ax = plt.subplots(figsize=(7., 3.6))
    
    ax.scatter(x, y, marker='o', color='b', s=40, zorder=10)
    xx = np.linspace(2.1, 3.9, 100)
    ax.plot(xx, c*xx**3.0, color='#CC0000', lw=3, zorder=5)
    for cc in [0.25*c, 0.5*c, 2.0*c, 4.0*c]:
        ax.plot(xx, cc*xx**3.0, color='#FF9900', lw=2, zorder=5)
    
    ax.spines["right"].set_visible(False)
    ax.spines["top"].set_visible(False)
    ax.yaxis.set_ticks_position('left')
    ax.xaxis.set_ticks_position('bottom')
    ax.tick_params(direction="out", width=1.25)
    ax.tick_params(direction="out", width=1.25)
    ax.set_xlabel('Size x / m')
    ax.set_ylabel('Weight y / kg')
    ax.set_xlim(2, 4)
    ax.set_ylim(0, 400)
    ax.set_xticks(np.arange(2.0, 4.1, 0.5))
    ax.set_yticks(np.arange(0, 401, 100))
    
    fig.set_facecolor("white")
    fig.subplots_adjust(0.11, 0.16, 0.98, 0.97)
    fig.savefig("cubicfunc.pdf")
    plt.close()