为什么这段代码中出现了“未定义名称'gini‘”的错误？

Question

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我似乎搞不懂为什么会有错误。我正在学习决策树算法。

def gini(rows):
    """calculate the gini impurity for a list of rows."""
    
    counts = class_counts(rows)
    impurity  = 1
    for lbl in counts:
        prob_of_lbl = counts[lbl] / float(len(rows))
        impurity -= prob_of_lbl**2
    return impurity

def info_gain(left, right, current_uncertainty):
    """Information Gain"""
    
    #The uncertainty of the starting node, minus the weighted
    #impurity of two child nodes.
    
    p = float(len(left)) / (len(left) + len(right))
    return current_uncertainty - p * gini(left) - (1 - p) * gini(right)

Answer 1

您在def gini ...之前有缩进吗？如果您的gini函数位于类中，则应该使用ClassName.gini。

例如：

class ClassName:
    def gini(rows):
        ...
    def info_gain(left, right, current_uncertainty):
        ...
        ClassName.gini(rows)
        ...