r. Adding Marginal plots

This lesson shows how to add marginal plots to an existing matplotlib axes

# sphinx_gallery_thumbnail_number = 2

import numpy as np
from easy_mpl import plot
from easy_mpl import regplot
import matplotlib.pyplot as plt
from easy_mpl.utils import version_info
from easy_mpl.utils import AddMarginalPlots

version_info()

{'easy_mpl': '0.21.4', 'matplotlib': '3.8.0', 'numpy': '1.26.1', 'pandas': '2.1.1', 'scipy': '1.11.3'}

We can add marginal plots to our main plot using AddMarginalPlots class. The marginal plots are used to show the distribution of x-axis data and y-axis data. The distribution of x-axis data is shown on top of main plot and the distribution of y-axis data is shown on right side of main plot.

x = np.random.normal(size=100)
y = np.random.normal(size=100)
e = x-y

ax = plot(
    e,
    'o',
    show=False,
    markerfacecolor=np.array([225, 121, 144])/256.0,
    markeredgecolor="black", markeredgewidth=0.5,
    ax_kws=dict(
        xlabel="Predicted",
        ylabel="Residual",
        xlabel_kws={"fontsize": 14},
        ylabel_kws={"fontsize": 14}),
     )

# draw horizontal line on y=0
ax.axhline(0.0)
AddMarginalPlots(ax)(x, y)
plt.show()

rng = np.random.default_rng(313)

x = rng.uniform(0, 10, size=100)
y = x + rng.normal(size=100)


# We can show distribution of x and y along the marginals
# This can be done by setting the ``marginals`` keyword to True

RIDGE_LINE_KWS = [{'color': 'olive', 'lw': 1.0}, {'color': 'firebrick', 'lw': 1.0}]
HIST_KWS = [{'color': 'khaki'}, {'color': 'salmon'}]

_ = regplot(x, y,
             marker_size = 35,
             marker_color='crimson',
             line_color='k',
             fill_color='k',
             scatter_kws={'edgecolors':'black', 'linewidth':0.5,
                          },
             marginals=True,
             marginal_ax_pad=0.25,
             marginal_ax_size=0.7,
             ridge_line_kws=RIDGE_LINE_KWS,
             hist=True,
             hist_kws=HIST_KWS)

Instead of drawing histograms, we can decide to fill the ridges drawn by kde lines on marginals.

fill_kws = [{'color': 'thistle'}, {'color': 'lightblue'}]
RIDGE_LINE_KWS1 = [{'color': 'purple', 'lw': 1.0}, {'color': 'teal', 'lw': 1.0}]

_ = regplot(x, y,
            marker_size = 40,
            marker_color='crimson',
            line_color='k',
            fill_color='k',
            scatter_kws={'edgecolors':'black', 'linewidth':0.5,
                          'alpha': 0.5},
            marginals=True,
            marginal_ax_pad=0.25,
            marginal_ax_size=0.7,
            ridge_line_kws=RIDGE_LINE_KWS1,
            hist=False,
            fill_kws=fill_kws)

multiple regression lines with customized marker, line and fill style

cov = np.array(
    [[1.0, 0.9, 0.7],
     [0.9, 1.2, 0.8],
     [0.7, 0.8, 1.4]]
)
data = rng.multivariate_normal(np.zeros(3),
                               cov, size=100)

ax = regplot(x, y, line_color='k',
             marker_color='orange', marker_size=35, fill_color='orange',
             scatter_kws={'edgecolors':'black', 'linewidth':0.8, 'alpha': 0.8},
             show=False, label="data 1")

axHistx, axHisty = AddMarginalPlots(
    ax, hist=False, fill_kws=fill_kws,
    ridge_line_kws=RIDGE_LINE_KWS
)(x, y)

fill_kws1 = [{'color': 'grey'}, {'color': 'royalblue'}]
_ = regplot(data[:, 0], data[:, 2], line_color='royalblue', ax=ax,
                marker_color='royalblue', marker_size=35, fill_color='royalblue',
             scatter_kws={'edgecolors':'black', 'linewidth':0.8, 'alpha': 0.8},
             show=False, label="data 2", ax_kws=dict(legend_kws=dict(loc=(0.1, 0.8))))

AddMarginalPlots(
    ax, hist=False,
    fill_kws=fill_kws1, ridge_line_kws=RIDGE_LINE_KWS1)(data[:, 0], data[:, 2], axHistx, axHisty)

plt.show()

Showing distributions using histograms

ax = regplot(x, y, line_color='k',
             marker_color='orange', marker_size=35, fill_color='orange',
             scatter_kws={'edgecolors':'black', 'linewidth':0.8, 'alpha': 0.8},
             show=False, label="data 1")

axHistx, axHisty = AddMarginalPlots(
    ax, ridge=False, hist_kws=HIST_KWS
)(x, y)

fill_kws1 = [{'color': 'grey'}, {'color': 'royalblue'}]
_ = regplot(data[:, 0], data[:, 2], line_color='royalblue', ax=ax,
                marker_color='royalblue', marker_size=35, fill_color='royalblue',
             scatter_kws={'edgecolors':'black', 'linewidth':0.8, 'alpha': 0.8},
             show=False, label="data 2", ax_kws=dict(legend_kws=dict(loc=(0.1, 0.8))))

HIST_KWS1 = {'alpha': 0.5}
AddMarginalPlots(
    ax, ridge=False, hist_kws=HIST_KWS1
)(data[:, 0], data[:, 2], axHistx, axHisty)

plt.show()