dials (version 0.0.2)

mtry: Parameter objects related to tree- and rule-based models.

Description

These are objects that can be used for modeling, especially in conjunction with the parsnip package.

Usage

mtry

mtry_long

trees

min_n

sample_size

learn_rate

loss_reduction

tree_depth

prune

Cp

Arguments

Value

Each object is generated by either new_quant_param or new_qual_param.

Format

An object of class quant_param (inherits from param) of length 7.

Details

These objects are pre-made parameter sets that are useful when the model is based on trees or rules.

  • mtry and mtry_long: The number of predictors that will be randomly sampled at each split when creating the tree models. The latter uses a log transformation and is helpful when the data set has a large number of columns. mtry is used by parsnip's parsnip::rand_forest() function.

  • trees: The number of trees contained in a random forest or boosted ensemble. In the latter case, this is equal to the number of boosting iterations. (see parsnip::rand_forest() and parsnip::boost_tree()) functions.

  • min_n: The minimum number of data points in a node that are required for the node to be split further. (parsnip::rand_forest() and parsnip::boost_tree())

  • sample_size: the size of the data set used for modeling within an iteration of the modeling algorithm, such as stochastic gradient boosting. (parsnip::boost_tree())

  • learn_rate: the rate at which the boosting algorithm adapts from iteration-to-iteration. (parsnip::boost_tree())

  • loss_reduction: The reduction in the loss function required to split further. (parsnip::boost_tree())

  • tree_depth: The maximum depth of the tree (i.e. number of splits). (parsnip::boost_tree())

  • prune: a logical for whether a tree or set of rules should be pruned.

  • Cp: The cost-complexity parameter in classical CART models.