Quick Start

This guide provides a quick introduction to plotting with scikit-plots.

1. Install Scikit-plots: - Use pip to install Scikit-plots:

   >>> pip install scikit-plots
   

A Simple Example

Let’s start with a basic example where we use a Random Forest classifier to evaluate the digits dataset provided by Scikit-learn.

A common way to assess a classifier’s performance is through its confusion matrix. Here’s how we can do it:

1. Load the Dataset: We’ll use the digits dataset, which contains features and labels for classification.

2. Initialize the Classifier: Create a RandomForestClassifier with specified parameters.

3. Generate Predictions: Use cross_val_predict to obtain predicted labels through cross-validation. This function provides cross-validated estimates for each sample point, which helps in evaluating metrics like accuracy, precision, recall, and the confusion matrix.

4. Plot the Confusion Matrix: Use plot_classifier_eval to visualize the confusion matrix.

5. Display the Plot: Optionally, use show to display the plot.

Here’s the code to illustrate the process:

from sklearn.datasets import load_digits
X, y = load_digits(return_X_y=True)

from sklearn.ensemble import RandomForestClassifier
clf = RandomForestClassifier(n_estimators=5, max_depth=5, random_state=1)

from sklearn.model_selection import cross_val_predict
y_pred = cross_val_predict(clf, X, y)

import scikitplot as skplt
fig1 = skplt.metrics.plot_classifier_eval(
    y, y_pred,
    labels=np.unique(y),
    figsize=(8, 3.2),
    title='Confusion Matrix'
);

(Source code, png)

The resulting confusion matrix shows how well the classifier performs. In this case, it struggles with digits 1, 8, and 9. Fine-tuning the Random Forest’s hyperparameters might improve performance.

One More Example

Maximum flexibility. Compatibility with non-scikit-learn objects.

Although Scikit-plot is loosely based around the scikit-learn interface, you don’t actually need Scikit-learn objects to use the available functions. As long as you provide the functions what they’re asking for, they’ll happily draw the plots for you.

Use Tensorflow or Pytorch

Here’s a quick example to generate the precision-recall curves of a keras Keras classifier model on a sample dataset.

import os
os.environ['TF_CPP_MIN_LOG_LEVEL'] = '3'  # or any {'0', '1', '2'}
import numpy as np
import tensorflow as tf
from sklearn.datasets import load_digits
from sklearn.model_selection import train_test_split
import matplotlib.pyplot as plt
import scikitplot as skplt

# Load the digits dataset
X, y = load_digits(return_X_y=True)

# Split the dataset into training and validation sets
X_train, X_val, y_train, y_val = train_test_split(X, y, test_size=0.3, random_state=1)

# Convert labels to one-hot encoding
Y_train = tf.keras.utils.to_categorical(y_train)
Y_val = tf.keras.utils.to_categorical(y_val)

# Define a simple TensorFlow model
model = tf.keras.Sequential([
    tf.keras.layers.Input(shape=(X_train.shape[1],)),
    tf.keras.layers.Dense(64, activation='relu'),
    tf.keras.layers.Dense(32, activation='relu'),
    tf.keras.layers.Dense(10, activation='softmax')
])

# Compile the model
model.compile(optimizer='adam',
              loss='categorical_crossentropy',
              metrics=['accuracy'])

# Train the model
model.fit(
    X_train, Y_train,
    batch_size=64,
    epochs=10,
    validation_data=(X_val, Y_val),
    verbose=0
)

# Predict probabilities on the validation set
y_probas = model.predict(X_val)

# Plot precision-recall curves
skplt.metrics.plot_precision_recall(y_val, y_probas)
plt.show()

(Source code, png)

Just pass the ground truth labels and predicted probabilities to plot_precision_recall to generate the precision-recall curves. This method is flexible and works with any classifier that produces predicted probabilities, from Keras classifiers to NLTK Naive Bayes to XGBoost as long as you pass in the predicted probabilities in the correct format.

Now what?

The recommended way to start using Scikit-plot is to just go through the documentation for the various modules and choose which plots you think would be useful for your work.

Happy plotting!