aeon

aeon

Overview

aeon provides a unified scikit-learn-compatible API for time series ML tasks: classification, regression, clustering, segmentation, annotation, similarity search, and transformation. It follows the same fit(X, y) / predict(X) pattern as scikit-learn, where X is a 3D NumPy array of shape (n_instances, n_channels, n_timepoints). aeon curates state-of-the-art algorithms from the time series literature — ROCKET and its variants (MiniROCKET, MultiROCKET) for classification, k-means with DTW for clustering, CLASP for segmentation — and provides benchmarking tools for comparing algorithms across datasets. It is the community-maintained fork of sktime following the 2022 governance split.

When to Use

• Classifying ECG, EEG, accelerometer, or sensor time series using state-of-the-art algorithms
• Regressing a scalar target from a time series input (e.g., predicting patient severity from vital sign waveforms)
• Clustering time series by shape similarity when class labels are unavailable
• Detecting change points or segmenting a continuous recording into homogeneous intervals
• Extracting fixed-length feature vectors from variable-length time series for downstream ML
• Benchmarking time series algorithms on the UCR/UEA archive with reproducible comparisons
• Use sktime when you need a larger ecosystem or existing code depends on its API; use tslearn for DTW-focused work

Prerequisites

• Python packages: aeon, numpy, scikit-learn, matplotlib
• Data format: 3D NumPy array (n_instances, n_channels, n_timepoints) or 2D (n_instances, n_timepoints) for univariate
• Optional: numba (required for ROCKET, DTW — install via pip install aeon[all_extras])

pip install aeon
pip install aeon[all_extras]  # includes numba, statsmodels for full algorithm support

Quick Start

import numpy as np
from aeon.classification.convolution_based import RocketClassifier
from aeon.datasets import load_unit_test

# Load a small benchmark dataset
X_train, y_train = load_unit_test(split="train")  # shape: (n, 1, timepoints)
X_test, y_test = load_unit_test(split="test")

print(f"Train: {X_train.shape}, classes: {np.unique(y_train)}")

clf = RocketClassifier(num_kernels=500, random_state=42)
clf.fit(X_train, y_train)
accuracy = clf.score(X_test, y_test)
print(f"ROCKET accuracy: {accuracy:.3f}")

Core API

Module 1: Time Series Classification

30+ classifiers spanning convolution, dictionary, distance, feature, interval, and shapelet families.

import numpy as np
from aeon.datasets import load_unit_test
from aeon.classification.convolution_based import RocketClassifier, MiniRocketClassifier
from aeon.classification.distance_based import KNeighborsTimeSeriesClassifier
from aeon.classification.feature_based import Catch22Classifier
from sklearn.metrics import accuracy_score

X_train, y_train = load_unit_test(split="train")
X_test, y_test   = load_unit_test(split="test")

classifiers = {
    "ROCKET":    RocketClassifier(num_kernels=1000, random_state=42),
    "MiniROCKET": MiniRocketClassifier(random_state=42),
    "KNN-DTW":   KNeighborsTimeSeriesClassifier(n_neighbors=1, distance="dtw"),
    "Catch22":   Catch22Classifier(random_state=42),
}

for name, clf in classifiers.items():
    clf.fit(X_train, y_train)
    acc = accuracy_score(y_test, clf.predict(X_test))
    print(f"{name:15s}: {acc:.3f}")

# Multivariate classification (multiple channels)
from aeon.classification.convolution_based import MultiRocketMultivariateClassifier

# Synthetic multivariate time series: 100 instances, 3 channels, 50 timepoints
np.random.seed(0)
X_mv_train = np.random.randn(100, 3, 50)
y_mv_train = (X_mv_train[:, 0, :].mean(axis=1) > 0).astype(str)
X_mv_test  = np.random.randn(30, 3, 50)
y_mv_test  = (X_mv_test[:, 0, :].mean(axis=1) > 0).astype(str)

clf_mv = MultiRocketMultivariateClassifier(random_state=42)
clf_mv.fit(X_mv_train, y_mv_train)
print(f"Multivariate accuracy: {clf_mv.score(X_mv_test, y_mv_test):.3f}")

Module 2: Time Series Regression

Predict a continuous target from a time series input.

import numpy as np
from aeon.regression.convolution_based import RocketRegressor
from aeon.regression.distance_based import KNeighborsTimeSeriesRegressor
from sklearn.metrics import mean_squared_error

# Synthetic regression: predict the mean of each series
np.random.seed(42)
X_train = np.random.randn(200, 1, 100)
y_train = X_train[:, 0, :].mean(axis=1) + np.random.randn(200) * 0.1
X_test  = np.random.randn(50, 1, 100)
y_test  = X_test[:, 0, :].mean(axis=1) + np.random.randn(50) * 0.1

reg = RocketRegressor(num_kernels=500, random_state=42)
reg.fit(X_train, y_train)
y_pred = reg.predict(X_test)
mse = mean_squared_error(y_test, y_pred)
print(f"ROCKET regressor MSE: {mse:.4f}")

Module 3: Time Series Clustering

Group time series by shape similarity without class labels.

import numpy as np
from aeon.clustering.k_means import TimeSeriesKMeans
from aeon.clustering.k_medoids import TimeSeriesKMedoids

# Synthetic clustering dataset: 3 distinct shapes
np.random.seed(0)
n_per_class = 30
class_0 = np.sin(np.linspace(0, 2*np.pi, 50)) + np.random.randn(n_per_class, 1, 50)*0.1
class_1 = np.cos(np.linspace(0, 2*np.pi, 50)) + np.random.randn(n_per_class, 1, 50)*0.1
class_2 = np.linspace(0, 1, 50) + np.random.randn(n_per_class, 1, 50)*0.05
X = np.concatenate([class_0, class_1, class_2], axis=0)

# K-Means with DTW averaging
km = TimeSeriesKMeans(n_clusters=3, metric="dtw", averaging_method="ba",
                       random_state=42, n_init=3, max_iter=50)
labels = km.fit_predict(X)
print(f"Cluster sizes: {np.bincount(labels)}")
print(f"Cluster centers shape: {km.cluster_centers_.shape}")

Module 4: Segmentation and Change Point Detection

Detect boundaries between regimes in a continuous time series.

import numpy as np
from aeon.segmentation import ClaSPSegmenter, EAggloSegmenter

# Simulate signal with 3 segments
np.random.seed(0)
seg1 = np.random.randn(100) * 0.5 + 0
seg2 = np.random.randn(100) * 0.5 + 3
seg3 = np.random.randn(100) * 0.5 - 2
signal = np.concatenate([seg1, seg2, seg3])

# CLASP: Classification Score Profile segmentation
clasp = ClaSPSegmenter(period_length=10, n_change_points=2)
labels = clasp.fit_predict(signal)
change_points = clasp.change_points_
print(f"Detected change points: {change_points}")
# Expected near indices 100 and 200

Module 5: Transformation (Feature Extraction)

Convert time series into fixed-length feature vectors or transformed series.

import numpy as np
from aeon.transformations.collection.convolution_based import Rocket, MiniRocket
from aeon.transformations.collection.feature_based import Catch22
from sklearn.linear_model import RidgeClassifierCV
from sklearn.pipeline import Pipeline

np.random.seed(42)
X_train = np.random.randn(100, 1, 50)
y_train = (X_train[:, 0, :].mean(axis=1) > 0).astype(str)
X_test  = np.random.randn(30, 1, 50)

# ROCKET transform → Ridge classifier (the classic ROCKET pipeline)
rocket_pipe = Pipeline([
    ("rocket", Rocket(num_kernels=1000, random_state=42)),
    ("clf", RidgeClassifierCV(alphas=[0.1, 1.0, 10.0])),
])
rocket_pipe.fit(X_train, y_train)
print(f"ROCKET pipeline accuracy: {rocket_pipe.score(X_test, (X_test[:, 0, :].mean(axis=1) > 0).astype(str)):.3f}")

# Catch22: 22 canonical time series features per channel
catch22 = Catch22()
X_features = catch22.fit_transform(X_train)
print(f"Catch22 feature matrix: {X_features.shape}")  # (n_instances, 22)

Module 6: Dataset Loading and Benchmarking

from aeon.datasets import load_classification, load_from_tsf_file
from aeon.benchmarking.results_loaders import get_estimator_results_as_array
import numpy as np

# Load UCR/UEA dataset
X_train, y_train = load_classification("BasicMotions", split="train")
X_test, y_test   = load_classification("BasicMotions", split="test")
print(f"BasicMotions: train={X_train.shape}, classes={np.unique(y_train)}")

# Load custom .ts file (UCR format)
# X, y = load_from_tsf_file("my_dataset.ts")

# Compare to published benchmark results
# from aeon.benchmarking import plot_critical_difference_diagram

Key Concepts

Data Format Convention

aeon uses 3D NumPy arrays of shape (n_instances, n_channels, n_timepoints):

• n_instances: number of time series (like n_samples in sklearn)
• n_channels: number of variables per time series (1 for univariate)
• n_timepoints: length of each series (can differ between instances for unequal-length)

Scikit-learn expects 2D (n_samples, n_features). Use aeon's transformers to convert.

ROCKET Family

ROCKET (Random Convolutional Kernel Transform) randomly generates 10,000 convolutional kernels of varying lengths, dilations, and biases, then applies them to each series to extract PPV (proportion of positive values) and max features. These 20,000 features are then classified with a linear model. MiniROCKET uses fewer, fixed kernels and is ~75× faster than ROCKET with similar accuracy. MultiROCKET extends to multivariate series.

Common Workflows

Workflow 1: Cross-Validated Classifier Comparison

import numpy as np
from aeon.datasets import load_unit_test
from aeon.classification.convolution_based import RocketClassifier, MiniRocketClassifier
from aeon.classification.feature_based import Catch22Classifier
from sklearn.model_selection import cross_val_score

X, y = load_unit_test()  # Full dataset (train+test merged)

classifiers = {
    "ROCKET":     RocketClassifier(num_kernels=500, random_state=42),
    "MiniROCKET": MiniRocketClassifier(random_state=42),
    "Catch22":    Catch22Classifier(random_state=42),
}

print(f"Dataset: {X.shape}, classes: {np.unique(y)}")
for name, clf in classifiers.items():
    scores = cross_val_score(clf, X, y, cv=5, scoring="accuracy")
    print(f"{name:15s}: {scores.mean():.3f} ± {scores.std():.3f}")

Workflow 2: Pipeline with Preprocessing and Classification

import numpy as np
from aeon.datasets import load_unit_test
from aeon.transformations.collection.convolution_based import Rocket
from aeon.transformations.collection.normalize import TimeSeriesScaler
from sklearn.pipeline import Pipeline
from sklearn.linear_model import RidgeClassifierCV
from sklearn.preprocessing import StandardScaler

X_train, y_train = load_unit_test(split="train")
X_test, y_test   = load_unit_test(split="test")

# Normalize series → ROCKET features → Ridge
pipe = Pipeline([
    ("normalize", TimeSeriesScaler()),
    ("rocket",    Rocket(num_kernels=2000, random_state=42)),
    ("scale",     StandardScaler(with_mean=False)),
    ("clf",       RidgeClassifierCV(alphas=[0.01, 0.1, 1.0, 10.0])),
])

pipe.fit(X_train, y_train)
print(f"Pipeline accuracy: {pipe.score(X_test, y_test):.3f}")

Key Parameters

Parameter	Module/Class	Default	Range / Options	Effect
num_kernels	Rocket, RocketClassifier	10000	500–50000	Number of random kernels; more = better accuracy, slower
n_clusters	TimeSeriesKMeans	8	2–50	Number of clusters for K-Means
metric	TimeSeriesKMeans, KNN	"dtw"	"dtw", "euclidean", "msm", "twe"	Distance metric for similarity computation
n_change_points	ClaSPSegmenter	1	1–20	Expected number of change points to detect
period_length	ClaSPSegmenter	auto	5–100	Minimum segment length
n_neighbors	KNeighborsTimeSeriesClassifier	1	1–20	k for KNN; k=1 often best for time series
averaging_method	TimeSeriesKMeans	"ba"	"ba" (Barycentre), "mean"	Method for computing cluster prototypes
random_state	All stochastic	None	int	Seed for reproducibility

Common Recipes

Recipe: Export ROCKET Features to DataFrame for AutoML

import numpy as np
import pandas as pd
from aeon.transformations.collection.convolution_based import MiniRocket

np.random.seed(0)
X = np.random.randn(200, 1, 100)  # 200 univariate time series, length 100
y = (X[:, 0, :].mean(axis=1) > 0).astype(int)

transformer = MiniRocket(random_state=42)
X_features = transformer.fit_transform(X)  # shape: (200, 9996)

df = pd.DataFrame(X_features, columns=[f"f{i}" for i in range(X_features.shape[1])])
df["label"] = y
df.to_parquet("rocket_features.parquet", index=False)
print(f"Feature matrix: {df.shape}, saved to rocket_features.parquet")

Recipe: Load and Classify a Custom Dataset

import numpy as np
from aeon.classification.convolution_based import RocketClassifier

# Custom dataset: time series stored as 3D array
# Shape: (n_instances, n_channels, n_timepoints)
np.random.seed(42)
X_train = np.random.randn(150, 2, 80)  # 150 bivariate series, length 80
y_train = np.random.choice(["class_A", "class_B", "class_C"], 150)
X_test  = np.random.randn(50, 2, 80)
y_test  = np.random.choice(["class_A", "class_B", "class_C"], 50)

clf = RocketClassifier(num_kernels=2000, random_state=42)
clf.fit(X_train, y_train)
print(f"Test accuracy: {clf.score(X_test, y_test):.3f}")

# Save predictions
y_pred = clf.predict(X_test)
print(f"Predictions: {y_pred[:10]}")

Troubleshooting

Problem	Cause	Solution
ImportError: numba when using ROCKET	numba not installed	pip install aeon[all_extras] or pip install numba
Input shape error: expected 3D array	Passing 2D (n, t) instead of 3D (n, 1, t)	Reshape: X = X[:, np.newaxis, :]
KNN-DTW very slow on large datasets	DTW is O(n·m) per pair; all-pairs comparison is O(N²)	Use ROCKET instead for N>1000; or reduce series length
Clustering assigns all points to one cluster	Initial centroids too close or metric not suited	Set n_init=10; try different metric ("msm" or "euclidean")
load_classification fails with download error	Network timeout or dataset name typo	Check available datasets: aeon.datasets.list_datasets(); download manually
ClaSPSegmenter detects wrong number of change points	n_change_points too high or period_length wrong	Set period_length to expected minimum segment length; validate with known signal
Memory error with large panel dataset	ROCKET transforms require n_kernels × n_instances matrix	Reduce num_kernels; process in batches with partial_fit

Related Skills

• neurokit2 — time series generation (ECG, EDA) that feeds into aeon classifiers
• scikit-learn-machine-learning — sklearn-compatible downstream models for aeon features
• matplotlib-scientific-plotting — visualization of time series and classification results

References

• aeon documentation — API reference, algorithm catalog, and tutorials
• aeon GitHub — source code, benchmarks, and contribution guide
• ROCKET paper: Dempster et al. (2020), DMKD — ROCKET algorithm description and UCR benchmark results
• MiniROCKET paper: Dempster et al. (2021), KDD — faster variant with comparable accuracy
• UCR Time Series Archive — 128 benchmark datasets for time series classification