title: Why estimator_weight in SAMME.R AdaBoost algorithm is set to 1
body: <p>I am new to AdaBoost algorithm. In <a href="https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/ensemble/weight_boosting.py" rel="nofollow noreferrer">sklearn</a> <strong>SAMME</strong> algorithm's _boost_discrete() <a href="https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/ensemble/weight_boosting.py#L583" rel="nofollow noreferrer">returns</a> classifiers weight as &quot;<strong>estimator_weight</strong>&quot;</p>
  <pre><code>def _boost_discrete(self, iboost, X, y, sample_weight):
      .......
  
      return sample_weight, estimator_weight, estimator_error
  </code></pre>
  <p>But, for <strong>SAMME.R</strong> algorithm, &quot;_boost_real()&quot; is <a href="https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/ensemble/weight_boosting.py#L530" rel="nofollow noreferrer">returning</a> '1' instead of returning the estimator weight.</p>
  <pre><code>def _boost_real(self, iboost, X, y, sample_weight):
      .......
  
      return sample_weight, 1., estimator_error
  </code></pre>
  <p>My question is why SAMME.R algorithm returning the estimator_weight as '1'.
  I am following ref [1]. Please help me understanding the algorithm. Thanks in advance.</p>
  <p>Ref:
  [1]J. Zhu, H. Zou, S. Rosset, T. Hastie, &quot;Multi-class AdaBoost&quot;, 2009.</p>