The ML Pipeline in PySpark
Learn how to build an ML Pipeline in PySpark for model training.
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The ML Pipeline in PySpark is a structured sequence of data processing and model training stages executed in a specific order. It offers an organized and systematic approach to building and deploying ML models, particularly in big data contexts.
Let’s explore the key concepts within Pipelines:
-
DataFrame: In PySpark’s ML API, the primary Dataset structure is
DataFrame
. Think of it as a versatile container capable of handling diverse data types, including text, feature vectors, labels, and predictions. Importantly,DataFrame
is distributed across clusters, making it well-suited for big data applications. -
Transformer: Transformers are key components within the ML Pipeline. They are responsible for modifying input
DataFrames
to produce transformed or augmented data. For instance, aTokenizer
Transformer splits text into individual words, a fundamental step in text analysis. Other examples includeVectorizers
andFeature
Transformers, each designed for specific data preprocessing tasks. -
Estimator: Estimators are the heart of the ML Pipeline. They are responsible for learning from input data to create predictive models. These models can include regression, classification, and clustering algorithms. For example, logistic regression is an Estimator used for binary classification tasks. Estimators provide a
fit
method to train on data, generating models that can later be used for making predictions. -
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