自定义一个函数,输入参数包括两个,一个为某个属性的所有属性值,另一个为属性值对应的标签,两个参数都为list类型;要求返回两个变量,变量1为最优划分中位点,另一个为最优划分中位点对应的最大信息增益。
时间: 2024-10-27 15:07:54 浏览: 35
在Python中,你可以创建一个名为`find_optimal_cut`的函数,用于解决这个问题。这个函数通常会涉及到一些数据挖掘或机器学习中的决策树算法,特别是ID3(Information Gain in Decision Trees)或C4.5算法。下面是一个简化版的伪代码示例:
```python
def find_optimal_cut(attribute_values, labels):
def calculate_entropy(labels):
# 计算给定标签列表的熵
entropy = 0.0
unique_labels = set(labels)
for label in unique_labels:
freq = labels.count(label) / len(labels)
entropy -= freq * math.log2(freq)
return entropy
def information_gain(left, right, current_attribute):
# 计算分割属性的信息增益
parent_entropy = calculate_entropy(labels)
left_entropy = calculate_entropy(left)
right_entropy = calculate_entropy(right)
gain = parent_entropy - (left_entropy * len(left) + right_entropy * len(right)) / len(labels)
return gain
best_cut = None
max_info_gain = float('-inf')
for i in range(len(attribute_values[0])):
# 对每个属性值,计算信息增益
cut_value = attribute_values[0][i] # 假设这里是数值型属性
left_values = [val for val, lab in zip(attribute_values, labels) if val <= cut_value]
right_values = [val for val, lab in zip(attribute_values, labels) if val > cut_value]
info_gain = information_gain(left_values, right_values, current_attribute)
if info_gain > max_info_gain:
max_info_gain = info_gain
best_cut = (cut_value, i)
return best_cut, max_info_gain
# 使用方法:
# attribute_values 示例:[['age', 'income'], [20, 50000], [30, 60000], [40, 70000]]
# labels 示例: ['high', 'low', 'high', 'low']
best_cut, max_info_gain = find_optimal_cut(attribute_values, labels)
```
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