Goto

Collaborating Authors

 Ensemble Learning


How Does the Random Forest Algorithm Work in Machine Learning

#artificialintelligence

In this article, you are going to learn the most popular classification algorithm. Which is the random forest algorithm. As a motivation to go further I am going to give you one of the best advantages of random forest. Random forest algorithm can use both for classification and the regression kind of problems. The Same algorithm both for classification and regression, You mind be thinking I am kidding.


Using ANNs on small data โ€“ Deep Learning vs. Xgboost

@machinelearnbot

Andrew Beam does a great job showing that small datasets are not off limits for current neural net methods. If you use the regularisation methods at hand โ€“ ANNs is entirely possible to use instead of classic methods. Let's see how this holds up on up on some benchmark datasets. Let's start with the iris dataset that you nicely can pull with the pandas read_csv function right of the internets. We create a feature matrix X and a target y from the Pandas dataframe.


Reviving Threshold-Moving: a Simple Plug-in Bagging Ensemble for Binary and Multiclass Imbalanced Data

arXiv.org Machine Learning

Class imbalance presents a major hurdle in the application of data mining methods. A common practice to deal with it is to create ensembles of classifiers that learn from resampled balanced data. For example, bagged decision trees combined with random undersampling (RUS) or the synthetic minority oversampling technique (SMOTE). However, most of the resampling methods entail asymmetric changes to the examples of different classes, which in turn can introduce its own biases in the model. Furthermore, those methods require a performance measure to be specified a priori before learning. An alternative is to use a so-called threshold-moving method that a posteriori changes the decision threshold of a model to counteract the imbalance, thus has a potential to adapt to the performance measure of interest. Surprisingly, little attention has been paid to the potential of combining bagging ensemble with threshold-moving. In this paper, we present probability thresholding bagging (PT-bagging), a versatile plug-in method that fills this gap. Contrary to usual rebalancing practice, our method preserves the natural class distribution of the data resulting in well calibrated posterior probabilities. We also extend the proposed method to handle multiclass data. The method is validated on binary and multiclass benchmark data sets. We perform analyses that provide insights into the proposed method.


Gradient Boosting โ€“ the coolest kid on the machine learning block

#artificialintelligence

Gradient boosting is a technique attracting attention for its prediction speed and accuracy, especially with large and complex data. Don't just take my word for it, the chart below shows the rapid growth of Google searches for xgboost (the most popular gradient boosting R package). From data science competitions to machine learning solutions for business, gradient boosting has produced best-in-class results. In this blog post I describe what it is and how to use it. Machine learning models can be fitted to data individually, or combined in an ensemble.


Boosting the accuracy of your Machine Learning models

#artificialintelligence

Boosting is here to help. Boosting is a popular machine learning algorithm that increases accuracy of your model, something like when racers use nitrous boost to increase the speed of their car. Boosting uses a base machine learning algorithm to fit the data. This can be any algorithm, but Decision Tree is most widely used. For an answer to why so, just keep reading.


Displayr Gradient Boosting - the coolest kid on the machine learning block

#artificialintelligence

Gradient boosting is a technique attracting attention for its prediction speed and accuracy, especially with large and complex data. As evidenced in the chart below showing the rapid growth of Google searches for xgboost (the best gradient boosting R package). From data science competitions to machine learning solutions for business, gradient boosting has produced best-in-class results. In this blog post I describe what it is and how to use it in Displayr. Gradient boosting is a type of boosting.


Improving Predictions with Ensemble Model

@machinelearnbot

"Alone we can do so little and together we can do much" - a phrase from Helen Keller during 50's is a reflection of achievements and successful stories in real life scenarios from decades. Same thing applies with most of the cases from innovation with big impacts and with advanced technologies world. The machine Learning domain is also in the same race to make predictions and classification in a more accurate way using so called ensemble method and it is proved that ensemble modeling offers one of the most convincing way to build highly accurate predictive models. Ensemble methods are learning models that achieve performance by combining the opinions of multiple learners. Typically, an ensemble model is a supervised learning technique for combining multiple weak learners or models to produce a strong learner with the concept of Bagging and Boosting for data sampling.


Walmart Competition: Trip Type Classification

@machinelearnbot

They took the NYC Data Science Academy 12-week full-time data science bootcamp program from Sep. 23 to Dec. 18, 2015. The post was based on their fourth in-class project (due after the 8th week of the program). Walmart uses trip type classification to segment its shoppers and their store visits to better improve the shopping experience. Walmart's trip types are created from a combination of existing customer insights and purchase history data. The purpose of the Kaggle competition is to use only the purchase data provided to derive Walmart's classification labels.


InfiniteBoost: building infinite ensembles with gradient descent

arXiv.org Machine Learning

In machine learning ensemble methods have demonstrated high accuracy for the variety of problems in different areas. The most known algorithms intensively used in practice are random forests and gradient boosting. In this paper we present InfiniteBoost -- a novel algorithm, which combines the best properties of these two approaches. The algorithm constructs the ensemble of trees for which two properties hold: trees of the ensemble incorporate the mistakes done by others; at the same time the ensemble could contain the infinite number of trees without the over-fitting effect. The proposed algorithm is evaluated on the regression, classification, and ranking tasks using large scale, publicly available datasets.


When Does Deep Learning Work Better Than SVMs or Random Forests?

@machinelearnbot

If we tackle a supervised learning problem, my advice is to start with the simplest hypothesis space first. I.e., try a linear model such as logistic regression. If this doesn't work "well" (i.e., it doesn't meet our expectation or performance criterion that we defined earlier), I would move on to the next experiment. I would say that random forests are probably THE "worry-free" approach - if such a thing exists in ML: There are no real hyperparameters to tune (maybe except for the number of trees; typically, the more trees we have the better). On the contrary, there are a lot of knobs to be turned in SVMs: Choosing the "right" kernel, regularization penalties, the slack variable, ... Both random forests and SVMs are non-parametric models (i.e., the complexity grows as the number of training samples increases).