c# - 重新创建 Accord.NET DecisionTree 网站示例 - 给定字典中不存在的键

Question

我严格按照 Accord.net 网站上的示例进行操作:

Link to the example, scroll to the bottom

我的代码是网站示例中代码的副本。我有正确的 NuGet 包。

  DataTable data = new DataTable("Mitchell's Tennis Example");

                data.Columns.Add("Day", "Outlook", "Temperature", "Humidity", "Wind", "PlayTennis");

                data.Rows.Add("D1", "Sunny", "Hot", "High", "Weak", "No");
                data.Rows.Add("D2", "Sunny", "Hot", "High", "Strong", "No");
                data.Rows.Add("D3", "Overcast", "Hot", "High", "Weak", "Yes");
                data.Rows.Add("D4", "Rain", "Mild", "High", "Weak", "Yes");
                data.Rows.Add("D5", "Rain", "Cool", "Normal", "Weak", "Yes");
                data.Rows.Add("D6", "Rain", "Cool", "Normal", "Strong", "No");
                data.Rows.Add("D7", "Overcast", "Cool", "Normal", "Strong", "Yes");
                data.Rows.Add("D8", "Sunny", "Mild", "High", "Weak", "No");
                data.Rows.Add("D9", "Sunny", "Cool", "Normal", "Weak", "Yes");
                data.Rows.Add("D10", "Rain", "Mild", "Normal", "Weak", "Yes");
                data.Rows.Add("D11", "Sunny", "Mild", "Normal", "Strong", "Yes");
                data.Rows.Add("D12", "Overcast", "Mild", "High", "Strong", "Yes");
                data.Rows.Add("D13", "Overcast", "Hot", "Normal", "Weak", "Yes");
                data.Rows.Add("D14", "Rain", "Mild", "High", "Strong", "No");

                // Create a new codification codebook to 
                // convert strings into integer symbols
                Codification codebook = new Codification(data);

                // Translate our training data into integer symbols using our codebook:
                DataTable symbols = codebook.Apply(data);
                int[][] inputs = symbols.ToArray<int>("Outlook", "Temperature", "Humidity", "Wind");
                int[] outputs = symbols.ToArray<int>("PlayTennis");

                // Gather information about decision variables
                DecisionVariable[] attributes =
    {
      new DecisionVariable("Outlook",     3), // 3 possible values (Sunny, overcast, rain)
      new DecisionVariable("Temperature", 3), // 3 possible values (Hot, mild, cool)  
      new DecisionVariable("Humidity",    2), // 2 possible values (High, normal)    
      new DecisionVariable("Wind",        2)  // 2 possible values (Weak, strong) 
    };

                int classCount = 2; // 2 possible output values for playing tennis: yes or no

                //Create the decision tree using the attributes and classes
                DecisionTree tree = new DecisionTree(attributes, classCount);

                // Create a new instance of the ID3 algorithm
                ID3Learning id3learning = new ID3Learning(tree);

                // Learn the training instances!
                id3learning.Run(inputs, outputs);

                string answer = codebook.Translate("PlayTennis",
                    tree.Compute(codebook.Translate("Sunny", "Hot", "High", "Strong")));

                Console.WriteLine("Calculate for: Sunny, Hot, High, Strong");
                Console.WriteLine("Answer: " + answer);

我得到这个异常:

The given key was not present in the dictionary.

在这行代码中:

string answer = codebook.Translate("PlayTennis",
                tree.Compute(codebook.Translate("Sunny", "Hot", "High", "Strong")));

我从哪里开始解决这个问题？我已经检查了调试器中的密码本，它包含了应有的元素。

Answer 1

框架文档似乎有点过时了。而不是将字典创建为

Codification codebook = new Codification(data);

框架现在期望用户在 Codification 的构造函数中传递感兴趣的列。因此，Codification 字典现在应该创建为

Codification codebook = new Codification(data, 
    "Outlook", "Temperature", "Humidity", "Wind", "PlayTennis");

文档将在几天内重建!