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| RandomForestOptions Class Reference Machine Learning |

Options object for the random forest. More...

`#include <vigra/random_forest/rf_common.hxx>`

## Public Member Functions

RandomForestOptions & | features_per_node (RF_OptionTag in)
| use built in mapping to calculate mtry More...
RandomForestOptions & | features_per_node (int in)
| Set mtry to a constant value. More...
RandomForestOptions & | features_per_node (int(*in)(int))
| use a external function to calculate mtry More...
RandomForestOptions & | min_split_node_size (int in)
| Number of examples required for a node to be split. More...
RandomForestOptions & | predict_weighted ()
| weight each tree with number of samples in that node
| RandomForestOptions ()
| create a RandomForestOptions object with default initialisation. More...
RandomForestOptions & | sample_with_replacement (bool in)
| sample from training population with or without replacement? More...
RandomForestOptions & | samples_per_tree (double in)
| specify the fraction of the total number of samples used per tree for learning. More...
RandomForestOptions & | samples_per_tree (int in)
| directly specify the number of samples per tree
RandomForestOptions & | samples_per_tree (int(*in)(int))
| use external function to calculate the number of samples each tree should be learnt with. More...
RandomForestOptions & | tree_count (int in)
RandomForestOptions & | use_stratification (RF_OptionTag in)
| specify stratification strategy More...

## Public Attributes

sampling options
double | training_set_proportion_
int | training_set_size_
int(* | training_set_func_ )(int)
RF_OptionTag | training_set_calc_switch_
bool | sample_with_replacement_
RF_OptionTag | stratification_method_
general random forest options
these usually will be used by most split functors and stopping predicates
RF_OptionTag | mtry_switch_
int | mtry_
int(* | mtry_func_ )(int)
bool | predict_weighted_
int | tree_count_
int | min_split_node_size_
bool | prepare_online_learning_

## Detailed Description

Options object for the random forest.

usage: RandomForestOptions a = RandomForestOptions() .param1(value1) .param2(value2) ...

This class only contains options/parameters that are not problem dependent. The ProblemSpec class contains methods to set class weights if necessary.

Note that the return value of all methods is *this which makes concatenating of options as above possible.

## Constructor & Destructor Documentation

## ◆ RandomForestOptions()

RandomForestOptions | ( |  | ) |

create a RandomForestOptions object with default initialisation.

look at the other member functions for more information on default values

## Member Function Documentation

## ◆ use_stratification()

RandomForestOptions& use_stratification | ( | RF_OptionTag | in | ) |

specify stratification strategy

default: RF_NONE possible values: RF_EQUAL, RF_PROPORTIONAL, RF_EXTERNAL, RF_NONE RF_EQUAL: get equal amount of samples per class. RF_PROPORTIONAL: sample proportional to fraction of class samples in population RF_EXTERNAL: strata_weights_ field of the ProblemSpec_t object has been set externally. (defunct)

## ◆ sample_with_replacement()

RandomForestOptions& sample_with_replacement | ( | bool | in | ) |

sample from training population with or without replacement?

Default: true

## ◆ samples_per_tree() [1/2]

RandomForestOptions& samples_per_tree | ( | double | in | ) |

specify the fraction of the total number of samples used per tree for learning.

This value should be in [0.0 1.0] if sampling without replacement has been specified.

default : 1.0

## ◆ samples_per_tree() [2/2]

RandomForestOptions& samples_per_tree | ( | int(*)(int) | in | ) |

use external function to calculate the number of samples each tree should be learnt with.

Parameters

  in | function pointer that takes the number of rows in the learning data and outputs the number samples per tree.

## ◆ features_per_node() [1/3]

RandomForestOptions& features_per_node | ( | RF_OptionTag | in | ) |

use built in mapping to calculate mtry

Use one of the built in mappings to calculate mtry from the number of columns in the input feature data.

Parameters

  in | possible values: RF_LOG, RF_SQRT or RF_ALL default: RF_SQRT.

## ◆ features_per_node() [2/3]

RandomForestOptions& features_per_node | ( | int | in | ) |

Set mtry to a constant value.

mtry is the number of columns/variates/variables randomly chosen to select the best split from.

## ◆ features_per_node() [3/3]

RandomForestOptions& features_per_node | ( | int(*)(int) | in | ) |

use a external function to calculate mtry

Parameters

  in | function pointer that takes int (number of columns of the and outputs int (mtry)

## ◆ tree_count()

RandomForestOptions& tree_count | ( | int | in | ) |

How many trees to create?

Default: 255.

## ◆ min_split_node_size()

RandomForestOptions& min_split_node_size | ( | int | in | ) |

Number of examples required for a node to be split.

When the number of examples in a node is below this number, the node is not split even if class separation is not yet perfect. Instead, the node returns the proportion of each class (among the remaining examples) during the prediction phase.
Default: 1 (complete growing)

The documentation for this class was generated from the following file:

- vigra/random_forest/rf_common.hxx

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python vigra 1.11.0