Source code for Orange.classification.simple_random_forest

import numpy as np

from Orange.classification import Learner, Model
from Orange.classification.simple_tree import SimpleTreeLearner

__all__ = ['SimpleRandomForestLearner']

[docs] class SimpleRandomForestLearner(Learner): """ A random forest classifier, optimized for speed. Trees in the forest are constructed with :obj:`SimpleTreeLearner` classification trees. Parameters ---------- n_estimators : int, optional (default = 10) Number of trees in the forest. min_instances : int, optional (default = 2) Minimal number of data instances in leaves. When growing the three, new nodes are not introduced if they would result in leaves with fewer instances than min_instances. Instance count is weighed. max_depth : int, optional (default = 1024) Maximal depth of tree. max_majority : float, optional (default = 1.0) Maximal proportion of majority class. When this is exceeded, induction stops (only used for classification). skip_prob : string, optional (default = "sqrt") Data attribute will be skipped with probability ``skip_prob``. - if float, then skip attribute with this probability. - if "sqrt", then `skip_prob = 1 - sqrt(n_features) / n_features` - if "log2", then `skip_prob = 1 - log2(n_features) / n_features` seed : int, optional (default = 42) Random seed. """ name = 'simple rf class' def __init__(self, n_estimators=10, min_instances=2, max_depth=1024, max_majority=1.0, skip_prob='sqrt', seed=42): super().__init__() self.n_estimators = n_estimators self.skip_prob = skip_prob self.max_depth = max_depth self.min_instances = min_instances self.max_majority = max_majority self.seed = seed
[docs] def fit_storage(self, data): return SimpleRandomForestModel(self, data)
class SimpleRandomForestModel(Model): def __init__(self, learner, data): self.estimators_ = [] self.cls_vals = len(data.domain.class_var.values) self.learn(learner, data) def learn(self, learner, data): tree = SimpleTreeLearner( learner.min_instances, learner.max_depth, learner.max_majority, learner.skip_prob, True) for i in range(learner.n_estimators): tree.seed = learner.seed + i self.estimators_.append(tree(data)) def predict(self, X): p = np.zeros((X.shape[0], self.cls_vals)) X = np.ascontiguousarray(X) # so that it is a no-op for individual trees for tree in self.estimators_: # SimpleTrees do not have preprocessors and domain conversion # was already handled within this class so we can call tree.predict() directly # instead of going through tree.__call__ _, pt = tree.predict(X) p += pt p /= len(self.estimators_) return p.argmax(axis=1), p