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Questions tagged [pruning]

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What is the objective function in cost-complexity pruning in rpart for classification tree?

I constructed a classification tree and want to prune it by using cost-complexity pruning in the rpart package. The objective function of cost-complexity prunig is C(T)=L(T)+a|T|. For regression tree ...
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2answers
146 views

Neural network's weight reduction

Are there any algorithms/methods for taking a trained model and reducing its number of weights with as little negative effect as possible to its final performance? Say I have a very big (too big) ...
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Determining alpha for pruning trees with cross-validation

following the answer from of Steffen to the question below: How to choose $\alpha$ in cost-complexity pruning? and slide 10 in: https://web.stanford.edu/class/stats202/content/lec19.pdf I'm still ...
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1answer
151 views

Cost complexity pruning and prediction error

I am reading the book titled "An Introduction to Statistical Learning" by James et al. There it is mentioned on page 309 that we pick the cost complexity parameter α to minimize the average Mean ...
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Cross-Validation of a pruned classification tree in r

I have a dataset with 358 observations and 22 variables. The prediction is about the existence or non-existence of a disease. A simple Classification tree with training and test split is giving an ...
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1answer
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Post-Pruning in partykit: the size of mob() tree

I am trying to build a multiple regression model while partitioning my data into subgroups based on additional set of covariates. While I implemented lmtree() or mob() in the "partykit" package, I ...
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1answer
921 views

How to obtain regularization parameter when pruning decision trees?

I'm having trouble understanding exactly how to obtain the regularization parameter when pruning a decision tree with the minimal cost complexity approach. Assume the cost complexity function is ...
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0answers
78 views

Machine Learning and Flow Maximization

Has anyone ever seen machine learning (ML) used to assist a Max Flow algorithm? I have a very large directed graph that has some fractal characteristics, meaning that this large graph can be roughly ...
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2answers
4k views

How to choose $\alpha$ in cost-complexity pruning?

In the following lectures Tree Methods, they describe a tree algorithm for cost complexity pruning on page 21. It says we apply cost complexity pruning to the large tree in order to obtain a sequence ...
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pruning : why if T1 and T2 (2 subtrees) with the same risk imply that one must be a subree of the other

I don't understand the following assertion from "An Introduction to Recursive Partitioning" page 13. If T1 and T2 are sub trees of T with Rα(T1) = Rα(T2), then either T1 is a sub tree of T2 or ...
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1answer
1k views

Avoiding overfitting with linear regression trees

I use regression trees (R package rpart) in my statistical analysis, and have received a critical comment that this method amounts to a "hunting expedition" that will always produce a result ("...