y_train_pred = y_train_pred.reshape(1, -1)是什么意思
时间: 2023-10-06 14:06:40 浏览: 87
这行代码的作用是将y_train_pred的形状从原来的一维数组(或者说行向量)转换为一个具有一行多列的二维数组。
其中,参数"1"表示第一维的大小为1,即只有一行;而参数"-1"表示第二维的大小自动调整,以保证总元素个数不变。实际上,"-1"的值会被自动计算为原始数组中元素的总个数,除以第一维的大小,也就是1。
这样做的目的可能是为了方便后续的计算或者其他操作,因为很多函数或方法要求输入的数据必须是二维数组,而一维数组则不符合要求。
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train_errors = [] test_errors = [] for lambda_val in lambdas: pipeline = Pipeline([ ('polynomial_features', PolynomialFeatures(degree=5)), ('ridge_regression', c.SGDLinearRegressor(batch_size=20, eta=0.01, tau_max=1000, epsilon=0.00001, lambda_=lambda_val, random_state=42))]) train_mse = 0 test_mse = 0 for i in range(10): X_train, y_train = c.generate_data(20) X_test, y_test = c.generate_data(1000) pipeline.fit(X_train.reshape(-1, 1), y_train) y_train_pred = pipeline.predict(X_train.reshape(-1, 1)) y_test_pred = pipeline.predict(X_test.reshape(-1, 1)) train_mse += mean_squared_error(y_train, y_train_pred) test_mse += mean_squared_error(y_test, y_test_pred) train_errors.append(train_mse / 10) test_errors.append(test_mse / 10)给这段代码加注释
下面是加了注释的代码:
```python
# 定义两个空列表,用于存储不同正则化参数下的训练误差和测试误差
train_errors = []
test_errors = []
# 遍历一系列正则化参数值
for lambda_val in lambdas:
# 定义管道对象,包含多项式特征转换和SGD线性回归模型
pipeline = Pipeline([
('polynomial_features', PolynomialFeatures(degree=5)),
('ridge_regression', c.SGDLinearRegressor(batch_size=20, eta=0.01, tau_max=1000,
epsilon=0.00001, lambda_=lambda_val, random_state=42))
])
# 定义训练误差和测试误差
train_mse = 0
test_mse = 0
# 对每个正则化参数值进行10次训练和测试
for i in range(10):
# 生成20个训练样本和对应标签,1000个测试样本和对应标签
X_train, y_train = c.generate_data(20)
X_test, y_test = c.generate_data(1000)
# 在训练集上拟合模型
pipeline.fit(X_train.reshape(-1, 1), y_train)
# 在训练集和测试集上进行预测
y_train_pred = pipeline.predict(X_train.reshape(-1, 1))
y_test_pred = pipeline.predict(X_test.reshape(-1, 1))
# 计算并累加训练误差和测试误差
train_mse += mean_squared_error(y_train, y_train_pred)
test_mse += mean_squared_error(y_test, y_test_pred)
# 将每个正则化参数值下的训练误差和测试误差除以10,并存储到对应的列表中
train_errors.append(train_mse / 10)
test_errors.append(test_mse / 10)
```
注释中解释了代码的每个部分的作用和功能,包括定义列表、遍历正则化参数、定义管道对象、生成数据、拟合模型、预测,以及计算训练误差和测试误差。通过注释,可以更加清晰地理解代码的功能和执行流程。
# 实现高斯核函数 def rbf_kernel(x1, x2): sigma=1.0 return np.exp(-np.linalg.norm(x1-x2,2)**2/sigma) # 加载葡萄酒识别数据集 wine = datasets.load_wine() # 处理数据和标签 X= wine["data"][:,(0,1)] y = 2 * (wine["target"]==1).astype(np.int64).reshape(-1,1) - 1 # 按照一定比例划分训练集和测试集(测试集占0.4) X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.4, random_state=5) # 定义KernelSVM模型 # 训练模型 # 用Pyplot作图工具绘制模型预测边界 x0s = np.linspace(10, 15, 100) x1s = np.linspace(0, 7, 100) x0, x1 = np.meshgrid(x0s, x1s) W = np.c_[x0.ravel(), x1.ravel()] u= model.predict(W).reshape(x0.shape) plt.plot(X_train[:, 0][y_train[:,0]==1] , X_train[:, 1][y_train[:,0]==1], "gs") plt.plot(X_train[:, 0][y_train[:,0]==-1], X_train[:, 1][y_train[:,0]==-1], "ro") plt.contourf(x0, x1, u, alpha=0.2) plt.show() #计算指标 from sklearn.metrics import accuracy_score from sklearn.metrics import recall_score from sklearn.metrics import precision_score from sklearn.metrics import f1_score accuracy = accuracy_score(y_test, y_pred) precision = precision_score(y_test, y_pred) recall = recall_score(y_test, y_pred) f1 = f1_score(y_test, y_pred) print("accuracy = {}".format(accuracy)) print("precision = {}".format(precision)) print("recall = {}".format(recall)) print("f1 = {}".format(f1))补全代码
抱歉,上面的代码仍然不完整,缺少了定义KernelSVM模型和训练模型的部分。以下是完整的代码:
```
# 实现高斯核函数
def rbf_kernel(x1, x2):
sigma=1.0
return np.exp(-np.linalg.norm(x1-x2,2)**2/sigma)
# 加载葡萄酒识别数据集
wine = datasets.load_wine()
# 处理数据和标签
X= wine["data"][:,(0,1)]
y = 2 * (wine["target"]==1).astype(np.int64).reshape(-1,1) - 1
# 按照一定比例划分训练集和测试集(测试集占0.4)
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.4, random_state=5)
# 定义KernelSVM模型
svm_clf = Pipeline([
("scaler", StandardScaler()),
("svm_clf", SVC(kernel="rbf", gamma=5, C=0.001))
])
# 训练模型
svm_clf.fit(X_train, y_train.ravel())
# 用Pyplot作图工具绘制模型预测边界
x0s = np.linspace(10, 15, 100)
x1s = np.linspace(0, 7, 100)
x0, x1 = np.meshgrid(x0s, x1s)
W = np.c_[x0.ravel(), x1.ravel()]
u= svm_clf.predict(W).reshape(x0.shape)
plt.plot(X_train[:, 0][y_train[:,0]==1] , X_train[:, 1][y_train[:,0]==1], "gs")
plt.plot(X_train[:, 0][y_train[:,0]==-1], X_train[:, 1][y_train[:,0]==-1], "ro")
plt.contourf(x0, x1, u, alpha=0.2)
plt.show()
# 计算指标
y_pred = svm_clf.predict(X_test)
accuracy = accuracy_score(y_test, y_pred)
precision = precision_score(y_test, y_pred)
recall = recall_score(y_test, y_pred)
f1 = f1_score(y_test, y_pred)
print("accuracy = {}".format(accuracy))
print("precision = {}".format(precision))
print("recall = {}".format(recall))
print("f1 = {}".format(f1))
```
其中,`SVC`是Scikit-Learn库中的SVM模型,`Pipeline`是Scikit-Learn库中的管道模型,用于将多个数据预处理和模型组合成一个整体。