fill_example.py

"""
Illustrate different ways of using the various fill functions.
"""
import numpy as np
import matplotlib.pyplot as plt

import example_utils

def main():
    fig, axes = example_utils.setup_axes()

    fill_example(axes[0])
    fill_between_example(axes[1])
    stackplot_example(axes[2])

    example_utils.title(fig, 'fill/fill_between/stackplot: Filled polygons',
                        y=0.95)
    fig.savefig('fill_example.png', facecolor='none')
    plt.show()

def fill_example(ax):
    # Use fill when you want a simple filled polygon between vertices
    x, y = fill_data()
    ax.fill(x, y, color='lightblue')
    ax.margins(0.1)
    example_utils.label(ax, 'fill')

def fill_between_example(ax):
    # Fill between fills between two curves or a curve and a constant value
    # It can be used in several ways. We'll illustrate a few below.
    x, y1, y2 = sin_data()

    # The most basic (and common) use of fill_between
    err = np.random.rand(x.size)**2 + 0.1
    y = 0.7 * x + 2
    ax.fill_between(x, y + err, y - err, color='orange')

    # Filling between two curves with different colors when they cross in
    # different directions
    ax.fill_between(x, y1, y2, where=y1>y2, color='lightblue')
    ax.fill_between(x, y1, y2, where=y1<y2, color='forestgreen')

    # Note that this is fillbetween*x*!
    ax.fill_betweenx(x, -y1, where=y1>0, color='red', alpha=0.5)
    ax.fill_betweenx(x, -y1, where=y1<0, color='blue', alpha=0.5)

    ax.margins(0.15)
    example_utils.label(ax, 'fill_between/x')

def stackplot_example(ax):
    # Stackplot is equivalent to a series of ax.fill_between calls
    x, y = stackplot_data()
    ax.stackplot(x, y.cumsum(axis=0), alpha=0.5)
    example_utils.label(ax, 'stackplot')

#-- Data generation ----------------------

def stackplot_data():
    x = np.linspace(0, 10, 100)
    y = np.random.normal(0, 1, (5, 100))
    y = y.cumsum(axis=1)
    y -= y.min(axis=0, keepdims=True)
    return x, y

def sin_data():
    x = np.linspace(0, 10, 100)
    y = np.sin(x)
    y2 = np.cos(x)
    return x, y, y2

def fill_data():
    t = np.linspace(0, 2*np.pi, 100)
    r = np.random.normal(0, 1, 100).cumsum()
    r -= r.min()
    return r * np.cos(t), r * np.sin(t)

main()