"""
========================
MATPLOTLIB **UNCHAINED**
========================

Comparative path demonstration of frequency from a fake signal of a pulsar.
(mostly known because of the cover for Joy Division's Unknown Pleasures)

Author: Nicolas P. Rougier
"""
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.animation as animation

# Create new Figure with black background
fig = plt.figure(figsize=(8, 8), facecolor="black")

# Add a subplot with no frame
ax = plt.subplot(111, frameon=False)

# Generate random data
data = np.random.uniform(0, 1, (64, 75))
X = np.linspace(-1, 1, data.shape[-1])
G = 1.5 * np.exp(-4 * X * X)

# Generate line plots
lines = []
for i in range(len(data)):
    # Small reduction of the X extents to get a cheap perspective effect
    xscale = 1 - i / 200.0
    # Same for linewidth (thicker strokes on bottom)
    lw = 1.5 - i / 100.0
    (line,) = ax.plot(xscale * X, i + G * data[i], color="w", lw=lw)
    lines.append(line)

# Set y limit (or first line is cropped because of thickness)
ax.set_ylim(-1, 70)

# No ticks
ax.set_xticks([])
ax.set_yticks([])

# 2 part titles to get different font weights
ax.text(
    0.5,
    1.0,
    "MATPLOTLIB ",
    transform=ax.transAxes,
    ha="right",
    va="bottom",
    color="w",
    family="sans-serif",
    fontweight="light",
    fontsize=16,
)
ax.text(
    0.5,
    1.0,
    "UNCHAINED",
    transform=ax.transAxes,
    ha="left",
    va="bottom",
    color="w",
    family="sans-serif",
    fontweight="bold",
    fontsize=16,
)


def update(*args):
    # Shift all data to the right
    data[:, 1:] = data[:, :-1]

    # Fill-in new values
    data[:, 0] = np.random.uniform(0, 1, len(data))

    # Update data
    for i in range(len(data)):
        lines[i].set_ydata(i + G * data[i])

    # Return modified artists
    return lines


# Construct the animation, using the update function as the animation
# director.
anim = animation.FuncAnimation(fig, update, interval=10)
plt.show()