mytree[bestFeatLabel][value] = createTree(splitDataSet(dataSet,bestFeat,value),new_label)
时间: 2024-01-02 17:01:42 浏览: 25
这是一个创建决策树节点的语句,用于在决策树中添加子节点。具体来说,`mytree`是决策树的字典,`bestFeatLabel`是当前节点的特征,`value`是当前特征的一个取值,`splitDataSet(dataSet,bestFeat,value)`是按照当前特征的取值对数据集进行划分,得到子数据集,`new_label`是剩余的特征标签,用于递归构建决策树。该语句的作用是创建一个决策树节点,并将其添加到决策树中。下面是该语句的语法格式:
```
字典名[键1][键2] = 值
```
其中`字典名`是字典的名称,`键1`是字典的键,可以是任何不可变类型的值,例如字符串、数字、元组等,`键2`也是字典的键,可以是任何不可变类型的值,例如字符串、数字、元组等,`值`是字典的值,可以是任何数据类型的值,例如整数、字符串、列表、字典等。该语句的作用是在字典中添加或修改一对键值对。在这段代码中,`mytree[bestFeatLabel][value]`表示在决策树中找到当前节点的字典,并创建一个以当前特征取值为键,对应子树为值的键值对,`createTree(splitDataSet(dataSet,bestFeat,value),new_label)`是递归调用`createTree`函数,构建子树,并将子树作为值赋给键值对。
相关问题
NameError Traceback (most recent call last) <ipython-input-5-66fc4f9977e5> in <module> 213 mytree = createTree(dataSet,labels) 214 print(f'决策树:{mytree}') --> 215 tree_plotter.create_plot(mytree) 216 217 #测试数据 NameError: name 'tree_plotter' is not defined
The error message "NameError: name 'tree_plotter' is not defined" suggests that the name "tree_plotter" was not defined in the code. In other words, the code is trying to call a function or variable named "tree_plotter" but it has not been defined or imported into the current scope.
To fix this error, you may need to check if the module or library containing the "tree_plotter" function has been imported correctly. You can try adding an import statement at the beginning of the code, for example:
```
import tree_plotter
```
If the "tree_plotter" function is part of a class or object, you may also need to make sure that you have created an instance of the class or object before calling the function.
Alternatively, if the "tree_plotter" function is not available in any module or library, you may need to define it yourself or find a suitable implementation online.
解释myTree = {bestfeat:{}}
这行代码定义了一个名为`myTree`的字典类型变量,其中包含一个键为`bestfeat`的字典。`bestfeat`是一个字符串类型的键,它的值是一个空的字典`{}`。通常,这种数据结构被用来表示决策树中的一个节点。在决策树中,每个节点都表示一个特征,而该节点下的子节点表示该特征的每个可能取值所对应的结果。在这里,`myTree`的`bestfeat`键表示当前节点的特征,而其值是该节点下的所有子节点。当这些子节点也是字典类型时,可以递归地构建整个决策树。