LEMON is a technique to explain why predictions of machine learning models are made. It does so by providing feature contribution: a score for each feature that indicates how much it contributed to the final prediction. More precisely, it shows the sensitivity of the feature: a small change in an important feature's value results in a relatively large change in prediction. It is similar to the popular LIME explanation technique, but is more faithful to the reference model, especially for larger datasets.

Website ↗ Academic paper ↗

Installation

To install use pip:

$ pip install lemon-explainer

Example

A minimal working example is shown below:

import numpy as np
import pandas as pd
from sklearn.datasets import load_iris
from sklearn.ensemble import RandomForestClassifier
from lemon import LemonExplainer

# Load dataset
data = load_iris(as_frame=True)
X = data.data
y = pd.Series(np.array(data.target_names)[data.target])

# Train complex model
clf = RandomForestClassifier()
clf.fit(X, y)

# Explain instance
explainer = LemonExplainer(X, radius_max=0.5)
instance = X.iloc[-1, :]
explanation = explainer.explain_instance(instance, clf.predict_proba)[0]
explanation.show_in_notebook()

Development

For a development installation (requires npm or yarn),

$ git clone https://github.com/iamDecode/lemon.git
$ cd lemon

You may want to (create and) activate a virtual environment:

$ python3 -m venv venv
$ source venv/bin/activate

Install requirements:

$ pip install -r requirements.txt

And run the tests with:

$ pytest .

Approximate distance kernel LIME

If you prefer to use a Gaussian distance kernel as used in LIME, we can approximate this behavior with:

from lemon import LemonExplainer, gaussian_kernel
from scipy.special import gammainccinv

DIMENSIONS = X.shape[1]
KERNEL_SIZE = np.sqrt(DIMENSIONS) * .75  # kernel size as used in LIME

# Obtain a distance kernel very close to LIME's gaussian kernel, see the paper for details.
p = 0.999
radius = KERNEL_SIZE * np.sqrt(2 * gammainccinv(DIMENSIONS / 2, (1 - p)))
kernel = lambda x: gaussian_kernel(x, KERNEL_SIZE)

explainer = LemonExplainer(X, distance_kernel=kernel, radius_max=radius)

This behavior is as close as possible to LIME, but still yields more faithful explanations due to LEMON's improved sampling technique. Read the paper for more details about this approach.

Citation

If you want to refer to our explanation technique, please cite our paper using the following BibTeX entry:

@inproceedings{collaris2023lemon,
  title={{LEMON}: Alternative Sampling for More Faithful Explanation Through Local Surrogate Models},
  author={Collaris, Dennis and Gajane, Pratik and Jorritsma, Joost and van Wijk, Jarke J and Pechenizkiy, Mykola},
  booktitle={Advances in Intelligent Data Analysis XXI: 21st International Symposium on Intelligent Data Analysis (IDA 2023)},
  pages={77--90},
  year={2023},
  organization={Springer}
}

License

This project is licensed under the BSD 2-Clause License - see the LICENSE file for details.