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scikit-learn (formerly scikits.learn and also known as sklearn) is a free and open-source machine learning library for the Python programming language. [3] It features various classification, regression and clustering algorithms including support-vector machines, random forests, gradient boosting, k-means and DBSCAN, and is designed to interoperate with the Python numerical and scientific ...
Most often, it is used for classification, as a k-NN classifier, the output of which is a class membership. An object is classified by a plurality vote of its neighbors, with the object being assigned to the class most common among its k nearest neighbors ( k is a positive integer , typically small).
Initialize model with a constant value: ^ () = = (,). [further explanation needed] Note that this is the initialization of the model and therefore we set a constant value for all inputs. So even if in later iterations we use optimization to find new functions, in step 0 we have to find the value, equals for all inputs, that minimizes the ...
Instead of decision trees, linear models have been proposed and evaluated as base estimators in random forests, in particular multinomial logistic regression and naive Bayes classifiers. [ 37 ] [ 38 ] [ 39 ] In cases that the relationship between the predictors and the target variable is linear, the base learners may have an equally high ...
A strong learner is a classifier that is arbitrarily well-correlated with the true classification. Robert Schapire answered the question in the affirmative in a paper published in 1990. [ 5 ] This has had significant ramifications in machine learning and statistics , most notably leading to the development of boosting.
Analogously, the model produced by SVR depends only on a subset of the training data, because the cost function for building the model ignores any training data close to the model prediction. Another SVM version known as least-squares support vector machine (LS-SVM) has been proposed by Suykens and Vandewalle.
Finally classifier is generated by using the previously created set of classifiers on the original dataset , the classification predicted most often by the sub-classifiers is the final classification for i = 1 to m { D' = bootstrap sample from D (sample with replacement) Ci = I(D') } C*(x) = argmax #{i:Ci(x)=y} (most often predicted label y) y∈Y
It gives a prediction model in the form of an ensemble of weak prediction models, i.e., models that make very few assumptions about the data, which are typically simple decision trees. [1] [2] When a decision tree is the weak learner, the resulting algorithm is called gradient-boosted trees; it usually outperforms random forest. [1]