sklearn.metrics.confusion_matrix的参数含义
时间: 2024-06-04 21:13:11 浏览: 10
sklearn.metrics.confusion_matrix是用来计算混淆矩阵的函数,它的两个参数含义如下:
1. y_true:实际值,是一个一维数组或者列表,代表每个样本的真实标签。
2. y_pred:预测值,是一个一维数组或者列表,代表每个样本的预测标签。
该函数的返回结果是一个混淆矩阵,是一个2x2的矩阵,每个元素代表着真实标签和预测标签的组合情况。
相关问题
from sklearn.metrics import confusion_matrix
As an AI language model, I cannot import libraries or execute code directly. However, I can provide information about the `confusion_matrix()` function from the `sklearn.metrics` module.
The `confusion_matrix()` function computes a confusion matrix which is a table that summarizes the performance of a classification algorithm. It takes two arguments:
- `y_true`: the true labels of the data, i.e., the ground truth.
- `y_pred`: the predicted labels of the data, i.e., the output of the classifier.
The function returns a NumPy array representing the confusion matrix. The rows of the matrix correspond to the true labels and the columns correspond to the predicted labels. Each element in the matrix represents the number of samples that were classified as a particular class. The diagonal elements represent the number of samples that were correctly classified for each class, while the off-diagonal elements represent the number of misclassified samples.
The confusion matrix is a useful tool for evaluating the performance of a classification algorithm, as it provides insight into which classes are being confused and how often. It can also be used to compute various evaluation metrics such as precision, recall, and F1-score.
sklearn.metrics中的plot_confusion_matrix用法示例
可以使用以下代码示例来使用sklearn.metrics中的plot_confusion_matrix函数:
```python
from sklearn.metrics import plot_confusion_matrix
from sklearn.datasets import make_classification
from sklearn.model_selection import train_test_split
from sklearn.svm import SVC
# 生成一个分类数据集
X, y = make_classification(random_state=0)
# 将数据集分为训练集和测试集
X_train, X_test, y_train, y_test = train_test_split(X, y, random_state=0)
# 训练一个SVM分类器
clf = SVC(random_state=0)
clf.fit(X_train, y_train)
# 使用plot_confusion_matrix函数绘制混淆矩阵
plot_confusion_matrix(clf, X_test, y_test)
```
这将绘制出测试集上的混淆矩阵,显示分类器的性能。
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