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Python 机器学习实践:测试驱动的开发方法
book

Python 机器学习实践:测试驱动的开发方法

by Matthew Kirk
January 2018
Intermediate to advanced content levelIntermediate to advanced
211 pages
8h 31m
Chinese
China Machine Press
Content preview from Python 机器学习实践:测试驱动的开发方法
74
5
方差缩减
方差缩减主要用于连续决策树。
从概念上讲方差缩减旨在减少分类的分散性。
虽然
它不适用于类似蘑菇是否可食用这种分类问题,但它适用于连续输出。我们宁愿有一
个以可预测的方式预测的模型:
Similarly:
I
G
Salty =
2
3
1−
2
3
+
1
2
1−
1
2
=
2
9
+
1
4
=
17
36
What this means is that the GINI impurity for Salty is higher than the GINI impurity
for Sweet. Intuitively while creating a decision tree we would want to choose Sweet as
a split point first, since it will create less impurity in the tree.
Variance Reduction
Variance reduction is used primarily in continuous decision trees. Conceptually var‐
iance reduction aims to reduce the dispersion of the classification. While it doesn’t
apply to classification problems such as whether mushrooms are edible or not, it ...
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Publisher Resources

ISBN: 9787111581666