Parallel Training

Larger datasets require more time for training. While by default the models in HiClass are trained using a single core, it is possible to train each local classifier in parallel by leveraging the library Ray 1. If Ray is not installed, the parallelism defaults to Joblib. In this example, we demonstrate how to train a hierarchical classifier in parallel by setting the parameter n_jobs to use all the cores available. Training is performed on a mock dataset from Kaggle 2.

1

https://www.ray.io/

2

https://www.kaggle.com/datasets/kashnitsky/hierarchical-text-classification

Pipeline(steps=[('count', CountVectorizer()), ('tfidf', TfidfTransformer()),
                ('lcppn',
                 LocalClassifierPerParentNode(local_classifier=LogisticRegression(max_iter=1000),
                                              n_jobs=2))])

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import sys
from os import cpu_count
from sklearn.feature_extraction.text import CountVectorizer, TfidfTransformer
from sklearn.linear_model import LogisticRegression
from sklearn.pipeline import Pipeline

from hiclass import LocalClassifierPerParentNode
from hiclass.datasets import load_hierarchical_text_classification

# Load train and test splits
X_train, X_test, Y_train, Y_test = load_hierarchical_text_classification()

# We will use logistic regression classifiers for every parent node
lr = LogisticRegression(max_iter=1000)

pipeline = Pipeline(
    [
        ("count", CountVectorizer()),
        ("tfidf", TfidfTransformer()),
        (
            "lcppn",
            LocalClassifierPerParentNode(local_classifier=lr, n_jobs=cpu_count()),
        ),
    ]
)

# Fixes bug AttributeError: '_LoggingTee' object has no attribute 'fileno'
# This only happens when building the documentation
# Hence, you don't actually need it for your code to work
sys.stdout.fileno = lambda: False

# Now, let's train the local classifier per parent node
pipeline.fit(X_train, Y_train)