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What is rpart method?
The rpart algorithm works by splitting the dataset recursively, which means that the subsets that arise from a split are further split until a predetermined termination criterion is reached.
Which algorithm does rpart use?
The rpart( ) function trains a classification regression decision tree using the Gini index as its class purity metric. Since this algorithm is different from the information entropy computation used in C5. 0, it may compute different splitting criterion for its decision trees.
What is CP in rpart?
The complexity parameter (cp) in rpart is the minimum improvement in the model needed at each node. For the given tree, add up the misclassification at every terminal node. Then multiply the number of splits time a penalty term (lambda) and add it to the total misclassification.
What is rpart Minsplit?
minsplit is “the minimum number of observations that must exist in a node in order for a split to be attempted” and minbucket is “the minimum number of observations in any terminal node”. Observe that rpart encoded our boolean variable as an integer (false = 0, true = 1).
How can text mining be used in R?
Got it! This post demonstrates how various R packages can be used for text mining in R. In particular, we start with common text transformations, perform various data explorations with term frequency (tf) and inverse document frequency (idf) and build a supervised classifiaction model that learns the difference between texts of different authors.
How to classify text in your using machine learning?
In this example we will provide R with a number of text documents, each document belonging to a category or “class”. We will use a number of machine learning algorithms to train different models. Finally we will use those models to classify new text.
How is term frequency used in text mining?
Term frequency is a useful measure to determine how frequently a word occurs in a document. There are words in a document, however, that occur many times but may not be important.
Can you classify text with are and RTextTools?
Before jumping into the code, there is something you need to be aware: RTextTools is a nice library, but it has not been updated in a while, as a result, many calls to it will fail. In order to fix that, I forked it and applied the required fixes, you will need to do three things