Multiple Color Scales

Use color_by/fill_by parameters and paint_a/paint_b/paint_c aesthetics if you need to display two different layers with the same color aesthetic but different color scales. Use new scale functions that allows to specify an aesthetic.

from lets_plot import *

LetsPlot.setup_html()

def generate_data(p1, p2, p3, p4, p5, x_max=400, y_max=300):
    import math

    def calculate_z(x, y):
        z = math.sin(x * p1 * math.pi / x_max)
        z += math.sin(y * p2 * math.pi / y_max)
        z += x * p3 / x_max
        z += y * p4 / y_max
        return z * p5

    x = []
    y = []
    z = []
    for row in range(y_max - 1):
        for col in range(x_max - 1):
            x.append(col)
            y.append(row)
            z.append(calculate_z(col, row))

    return dict(x=x, y=y, z=z)

height_data = generate_data(3, 3, 3, 5, 11)
temperature_data = generate_data(1, 2, 5, 4, -.5)

ggplot() + \
    geom_contour(aes('x', 'y', z='z', color='..level..'), \
                 data=height_data, bins=15, size=1) + \
    geom_contour(aes('x', 'y', z='z', paint_a='..level..'), \
                 data=temperature_data, color_by='paint_a', \
                 bins=8, size=1) + \
    scale_color_gradient(name="height", low="#993404", high="#ffffd4") + \
    scale_gradient('paint_a', name="temperature", low="#0571b0", high="#ca0020") + \
    ggsize(800, 600)