Snorkel
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Table of Content
At Stanford, Snorkel started in 2016 as a project that, according to the advisor's graduate student at the time, "should presumably take an afternoon." It turned out to be a lengthy afternoon (happy). In In the recent years, Snorkel has been utilized in several fields, including business (e.g., Google, Intel, IBM), medicine (e.g., Stanford, VA), government, and science; it has been the focus of more than twenty-four articles in machine learning, science, and systems, including six NeurIPS and ICML papers.
In addition to two papers in Nature Communications and a "Best Of" VLDB paper, the most satisfying aspect of all is that it has benefited from the suggestions and assistance of a lively and giving user community.
Learn the core concepts of Data Science Course video on YouTube:
What is Snorkel ML?
Snorkel ML is an open-source library for building and managing training data for machine learning models. It allows data scientists to create training data by labeling data programmatically or using weak supervision, such as heuristics, rules, and models.
Snorkel ML provides a variety of tools and utilities for labeling data, including labeling functions, which are user-defined functions that label data based on heuristics or rules, and labeling pipelines, which automate the labeling process.
1. Labeling Functions
2. Labeling Function Matrices
3. Iterative Labeling
4. Probabilistic Modelling`
5. Scalability
6. Flexibility
7. Data Augmentation
8. Active Learning
9. Integration with PyTorch
10. Integration with Other Tools
1. Labeling Functions:
Users of Snorkel can develop labelling functions, which are Python functions that output a label or refrain from labelling in accordance with some heuristic or criterion. You can implement domain knowledge and other heuristics into the labelling process by writing labelling functions however you choose.
2. Labeling Function Matrices:
Snorkel allows users to combine labeling functions into a labeling function matrix, which generates a single label for each data point based on the outputs of the labeling functions. This allows you to leverage the strengths of multiple labeling functions and generate high-quality training data even in cases where manual labeling is not feasible.
3. Iterative Labeling:
Snorkel supports an iterative labeling process, where the labels generated by the model are used to improve the accuracy of the labeling functions. This process is known as "bootstrapping" and involves iteratively training the model on the labels generated by the labeling functions and using the trained model to generate new labels.
4. Probabilistic Modeling:
Snorkel provides probabilistic modeling capabilities, allowing you to train a model that takes into account the outputs of multiple labeling functions to generate a more accurate label for each data point. This can improve the quality of your training data and the performance of your machine learning models.
5. Scalability:
Snorkel is designed to be scalable, allowing you to create large datasets quickly and easily. This can be especially useful in applications where large amounts of labeled data are required, such as in natural language processing, computer vision, and genomics.
6. Flexibility:
Snorkel is a flexible framework that can be used in a variety of applications and with a variety of data types. It can be used for text, image, and other types of data, and can be adapted to suit the needs of your specific application.
7. Data Augmentation:
Snorkel supports data augmentation, which allows you to create synthetic training data by applying transformations to your existing data. This can be especially useful in cases where you have a limited amount of labeled data.
8. Active Learning:
Snorkel supports active learning, which allows you to select the most informative examples to label manually, reducing the amount of manual labeling required.
9. Integration with PyTorch:
Snorkel is built on top of PyTorch, a popular deep learning framework, allowing you to easily integrate Snorkel with your PyTorch-based machine learning pipeline.
10. Integration with Other Tools:
Snorkel ML can be easily integrated with other machine learning tools, such as TensorFlow, PyTorch, and scikit-learn. This allows data scientists to use Snorkel ML with their existing machine learning workflows and tools.
Getting Started with Snorkel
To get started with Snorkel, you'll need to install it on your system. Snorkel is available on GitHub, and you can download it from there. Once you have Snorkel installed, you can start using it to label data and train machine learning models.
Snorkel provides several tools for managing training data, including a labeling interface, data cleaning tools, and a labeling function library. The labeling interface is used to view and label data, while the data cleaning tools help to remove errors and inconsistencies from the data. The labeling function library provides a collection of functions that can be used to programmatically label data.
How to Use Snorkel ML:
1. First, make sure you have Python 3.6 or later installed on your system. You can download Python from the official website.
2. Next, create a new virtual environment for Snorkel. You can do this using the venv module that comes with Python:
3. First, make sure you have Python 3.6 or later installed on your system. You can download Python from the official website.
4. Next, create a new virtual environment for Snorkel. You can do this using the venv module that comes with Python:
5. Activate the virtual environment:
6. Install Snorkel and its dependencies using pip:
7. Finally, test your installation by running the following command:
Creating a Labeling Function
Once Snorkel ML is installed, you can begin creating a labeling function. A labeling function is a user-defined function that labels data based on heuristics or rules.
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To create a labeling function in Snorkel ML, you can use the @labeling_function decorator. Here's an example labeling function that labels spam emails:
This labeling function checks if the word "free" appears in the email text. If it does, the function returns 1, indicating that the email is spam. Otherwise, the function returns 0.
Creating a Labeling Pipeline
After creating a labeling function, you can use it to create a labeling pipeline. A labeling pipeline is a set of labeling functions that are used to label data programmatically.
To create a labeling pipeline in Snorkel ML, you can use the LabelingFunction and LabelModel classes. Here's an example labeling pipeline that uses the spam email labeling function:
This labeling pipeline includes the spam email labeling function, which was created in the previous step. The labeling pipeline is then used to create a label model, which can be used to label new data.
Labeling New Data
After creating a labeling pipeline and label model, you can use them to label new data. To label new data, you can use the label method of the label model.
Here's an example of how to use the label model to label new data:
This code creates a pandas DataFrame with new data and applies the labeling pipeline to it. The label model is then used to label the new data using the output of the labeling pipeline.
Improving Machine Learning Accuracy
Use labeling functions to generate high-quality training data: Snorkel allows you to programmatically label training data using labeling functions, which can be written in any way you choose. By combining multiple labeling functions into a labeling function matrix, you can generate high-quality training data even in cases where manual labeling is not feasible.
Use iterative labeling to improve the accuracy of your labeling functions: Snorkel supports an iterative labeling process, where the labels generated by the model are used to improve the accuracy of the labeling functions. This process is known as "bootstrapping" and involves iteratively training the model on the labels generated by the labeling functions and using the trained model to generate new labels.
Use probabilistic modeling to generate more accurate labels: Snorkel provides probabilistic modeling capabilities, allowing you to train a model that takes into account the outputs of multiple labeling functions to generate a more accurate label for each data point.
Use data augmentation to increase the amount of labeled data: Snorkel supports data augmentation, which allows you to create synthetic training data by applying transformations to your existing data. This can be especially useful in cases where you have a limited amount of labeled data.
Use active learning to select the most informative examples to label manually: Snorkel supports active learning, which allows you to select the most informative examples to label manually, reducing the amount of manual labeling required.
Use model ensembling to improve the performance of your machine learning models: Snorkel allows you to train multiple models on different subsets of your training data and combine their outputs to generate a more accurate prediction.
here's an example of how to improve machine learning accuracy using Snorkel with some code:
In this example, we define two simple labeling functions lf_contains_good and lf_contains_bad that label sentences containing the words "good" and "bad" as positive and negative, respectively. We then apply these labeling functions to some training and test data, generate labels using the LFMatrix class, and train a LabelModel using the training labels.
We then use the LabelModel to predict labels for the test data, and evaluate the accuracy of the model by comparing the predicted labels to the true labels. In this case, the true labels are [1, -1, -1], and the predicted labels are [1, -1, -1], so the accuracy is 100%.
This is just a simple example, but Snorkel allows you to define much more complex labeling functions, combine them into powerful labeling function matrices, and train sophisticated machine learning models to generate high-quality predictions for a wide range of applications.
End to End SnorkelML with Basic Codings:
Prerequisites
Before diving into SnorkelML, some basic knowledge of Python is required. Additionally, users should have a working knowledge of machine learning concepts such as training and testing datasets, model selection, and evaluation metrics.
Installing SnorkelML
To install SnorkelML, first, you need to install Anaconda, a popular Python distribution that includes many data science packages. After installing Anaconda, you can create a new environment and install SnorkelML using the following commands:
Basic Codings
Here are some basic codings that will help you get started with SnorkelML:
Data Loading
Before training the model, the first step is to load the data. SnorkelML supports various data formats such as CSV, TSV, and JSON. Here is an example of loading data from a CSV file:
Labeling Data
The next step is to label the data. SnorkelML uses a weak supervision approach to label data, which means it uses heuristics or rules to automatically label data. Here is an example of labeling data using the Snorkel labeler:
Training the Model
After labeling the data, the next step is to train the model. SnorkelML supports various machine learning models such as Logistic Regression, Random Forest, and Support Vector Machines. Here is an example of training a Logistic Regression model:
Conclusion
Snorkel ML is a powerful tool for training machine learning models with limited labeled data. It allows data scientists to create labeled data programmatically, based on a set of user-defined rules or heuristics.
By using Snorkel ML, data scientists can improve the accuracy of their machine learning models and reduce the time and cost associated with manual labeling. Snorkel ML can also reduce the risk of bias in the training data by allowing data scientists to create labeled data using a variety of sources.
Certainly! The Snorkel ML blog explains the basics of Snorkel ML, its key features, and how it can be used to improve the accuracy of machine learning models. It starts by introducing Snorkel ML as an open-source library for building and managing training data for machine learning models, and describes how it allows data scientists to create labeled data programmatically or using weak supervision, such as heuristics, rules, and models. The blog then goes on to describe the key features of Snorkel ML, which include weak supervision, labeling functions, labeling pipelines, and integration with other tools.
The blog also explains how Snorkel ML can improve machine learning accuracy by allowing data scientists to create more labeled data with limited labeled data, which can be especially useful in situations where manual labeling is expensive or time-consuming. By using weak supervision to generate training data, Snorkel ML can also reduce the risk of bias in the training data.
The second half of the blog is a tutorial that explains how to use Snorkel ML to label data programmatically, create a labeling pipeline, and label new data. It also explains how data scientists can improve machine learning accuracy by using Snorkel ML to label data programmatically.
