R: Callback closure for resetting the booster's parameters at...

cb.reset.parameters {xgboost} | R Documentation

## Callback closure for resetting the booster's parameters at each iteration.

### Description

Callback closure for resetting the booster's parameters at each iteration.

### Usage

    cb.reset.parameters(new_params)

### Arguments

`new_params` | a list where each element corresponds to a parameter that needs to be reset. Each element's value must be either a vector of values of length `nrounds` to be set at each iteration, or a function of two parameters `learning_rates(iteration, nrounds)` which returns a new parameter value by using the current iteration number and the total number of boosting rounds.

### Details

This is a "pre-iteration" callback function used to reset booster's parameters at the beginning of each iteration.

Note that when training is resumed from some previous model, and a function is used to reset a parameter value, the `nrounds` argument in this function would be the the number of boosting rounds in the current training.

Callback function expects the following values to be set in its calling frame: `bst` or `bst_folds`, `iteration`, `begin_iteration`, `end_iteration`.

### See Also

`callbacks`

[Package xgboost version 0.82.0.1 Index]