How to parallelize machine learning algorithms in R

Deepanshu Bhalla 1 Comment

Running machine learning algorithms in parallel has several benefits, and it can be advantageous in various scenarios. Here are some reasons why parallelization is used in machine learning:

  • Faster Computation: Machine learning algorithms, especially those that involve extensive computations or large datasets, can be time-consuming. By running the algorithms in parallel, you can distribute the workload across multiple processors or machines, significantly reducing the training time. This is particularly useful when dealing with big data and complex models.
  • Scalability: Parallel machine learning allows you to scale your computations to handle larger datasets and more complex models. As the data size and model complexity increase, parallelization becomes crucial to maintain acceptable performance.
  • Resource Utilization: Parallelization enables efficient utilization of computational resources. Modern computers and servers often have multiple cores or processors, and parallel machine learning makes it possible to use these resources effectively.
  • Grid Search and Hyperparameter Tuning: When performing hyperparameter tuning using grid search or other optimization techniques, parallel execution can explore different hyperparameter combinations simultaneously. This speeds up the process of finding the best hyperparameters for your model.
  • Cross-Validation: Cross-validation is commonly used to evaluate machine learning models and assess their generalization performance. Parallelization can accelerate the cross-validation process by running multiple folds in parallel, leading to faster model evaluation.
  • Ensembling: In ensemble methods like bagging and boosting, multiple models are trained in parallel and combined to make predictions. Parallel execution of these models speeds up the ensemble training process.

In R, we can run machine learning algorithms in parallel mode using doParallel and caret packages.

The following code demonstrates how to use parallel computing using the doParallel package in combination with caret package in R to run a Random Forest model in parallel using multiple cores.

ctrl <- trainControl(method="repeatedcv", repeats=5, classProbs=TRUE)

#Run model in parallel
cl <- makeCluster(detectCores())

model = train(Species~., data = iris, method='rf', trControl= ctrl)

The makeCluster function creates a parallel cluster using the number of available CPU cores (detected using detectCores()). The registerDoParallel function registers this parallel backend, enabling parallel computations with the caret package.

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About Author:
Deepanshu Bhalla

Deepanshu founded ListenData with a simple objective - Make analytics easy to understand and follow. He has over 10 years of experience in data science. During his tenure, he worked with global clients in various domains like Banking, Insurance, Private Equity, Telecom and HR.

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