app.py

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.colors import ListedColormap
from itertools import combinations
from functools import partial

plt.rcParams['figure.dpi'] = 100

from sklearn.datasets import load_iris
from sklearn.ensemble import (
    RandomForestClassifier,
    ExtraTreesClassifier,
    AdaBoostClassifier,
)
from sklearn.tree import DecisionTreeClassifier

import gradio as gr

# ========================================

C1, C2, C3 = '#ff0000', '#ffff00', '#0000ff'
CMAP = ListedColormap([C1, C2, C3])
GRANULARITY = 0.01
SEED = 1
N_ESTIMATORS = 30

FEATURES = ["Sepal Length", "Sepal Width", "Petal Length", "Petal Width"]
LABELS = ["Setosa", "Versicolour", "Virginica"]
MODEL_NAMES = ['DecisionTreeClassifier', 'RandomForestClassifier', 'ExtraTreesClassifier', 'AdaBoostClassifier']

iris = load_iris()

MODELS = [
        DecisionTreeClassifier(max_depth=None),
        RandomForestClassifier(n_estimators=N_ESTIMATORS, n_jobs=-1),
        ExtraTreesClassifier(n_estimators=N_ESTIMATORS, n_jobs=-1),
        AdaBoostClassifier(DecisionTreeClassifier(max_depth=3), n_estimators=N_ESTIMATORS)
        ]

# ========================================

def create_plot(feature_string, n_estimators, max_depth, model_idx):
    np.random.seed(SEED)

    feature_list = feature_string.split(',')
    feature_list = [s.strip() for s in feature_list]
    idx_x = FEATURES.index(feature_list[0])
    idx_y = FEATURES.index(feature_list[1])

    X = iris.data[:, [idx_x, idx_y]]
    y = iris.target

    rnd_idx = np.random.permutation(X.shape[0])
    X = X[rnd_idx]
    y = y[rnd_idx]

    X = (X - X.mean(0)) / X.std(0)

    model_name = MODEL_NAMES[model_idx]
    model = MODELS[model_idx]

    if model_idx != 0: model.n_estimators = n_estimators
    if model_idx != 3: model.max_depth = max_depth
    if model_idx == 3: model.estimator.max_depth = max_depth
    
    model.fit(X, y)
    score = round(model.score(X, y), 3)

    x_min, x_max = X[:, 0].min() - 1, X[:, 0].max() + 1
    y_min, y_max = X[:, 1].min() - 1, X[:, 1].max() + 1
    xrange = np.arange(x_min, x_max, 0.1)
    yrange = np.arange(y_min, y_max, 0.1)
    xx, yy = np.meshgrid(xrange, yrange)

    Z = model.predict(np.c_[xx.ravel(), yy.ravel()])
    Z = Z.reshape(xx.shape)

    fig = plt.figure()
    ax = fig.add_subplot(111)

    ax.contourf(xx, yy, Z, cmap=CMAP, alpha=0.65)

    for i, label in enumerate(LABELS):
        X_label = X[y==i,:]
        y_label = y[y==i]
        ax.scatter(X_label[:, 0], X_label[:, 1], c=[[C1], [C2], [C3]][i]*len(y_label), edgecolor='k', s=40, label=label)

    ax.set_xlabel(feature_list[0]); ax.set_ylabel(feature_list[1])
    ax.legend()
    ax.set_title(f'{model_name} | Score: {score}')

    return fig

def iter_grid(n_rows, n_cols):
    for _ in range(n_rows):
        with gr.Row():
            for _ in range(n_cols):
                with gr.Column():
                    yield

info = '''
## Plot the decision surfaces of ensembles of trees on the Iris dataset

This plot compares the decision surfaces learned by a decision tree classifier, a random forest classifier, an extra-trees classifier, and by an AdaBoost classifier.

There are in total four features in the Iris dataset. In this example you can select two features at a time for visualization purposes using the dropdown box below.

You can also vary the number of estimators in the ensembles and the max depth of the trees using the sliders.
'''

with gr.Blocks() as demo:
    gr.Markdown(info)
    selections = combinations(FEATURES, 2)
    selections = [f'{s[0]}, {s[1]}' for s in selections] 
    dd = gr.Dropdown(selections, value=selections[0], interactive=True, label="Input features")
    slider_estimators = gr.Slider(1, 100, value=30, step=1, label='n_estimators')
    slider_max_depth = gr.Slider(1, 50, value=10, step=1, label='max_depth')

    counter = 0
    for _ in iter_grid(2, 2):
        if counter >= len(MODELS):
            break
        
        plot = gr.Plot(label=f'{MODEL_NAMES[counter]}')
        fn = partial(create_plot, model_idx=counter)

        dd.change(fn, inputs=[dd, slider_estimators, slider_max_depth], outputs=[plot])
        slider_estimators.change(fn, inputs=[dd, slider_estimators, slider_max_depth], outputs=[plot])
        slider_max_depth.change(fn, inputs=[dd, slider_estimators, slider_max_depth], outputs=[plot])
        demo.load(fn, inputs=[dd, slider_estimators, slider_max_depth], outputs=[plot])

        counter += 1

demo.launch(share=True, debug=True)