Python Seaborn混淆矩阵
SpikeKing 人气:0Seaborn - 绘制多标签的混淆矩阵、召回、精准、F1
导入seaborn\matplotlib\scipy\sklearn等包:
import seaborn as sns from matplotlib import pyplot as plt from scipy.special import softmax from sklearn.metrics import accuracy_score, confusion_matrix, precision_score, recall_score, f1_score sns.set_theme(color_codes=True)
从dataframe中,获取y_true(真实标签)和y_pred(预测标签):
y_true = df["target"] y_pred = df['prediction']
计算验证数据整体的准确率acc、精准率precision、召回率recall、F1,使用加权模式average=‘weighted’:
# 准确率acc,精准precision,召回recall,F1 acc = accuracy_score(df["target"], df['prediction']) precision = precision_score(y_true, y_pred, average='weighted') recall = recall_score(y_true, y_pred, average='weighted') f1 = f1_score(y_true, y_pred, average='weighted') print(f'[Info] acc: {acc}, precision: {precision}, recall: {recall}, f1: {f1}')
计算混淆矩阵:
# 横坐标是真实类别数,纵坐标是预测类别数 cf_matrix = confusion_matrix(y_true, y_pred)
5类矩阵的绘制方案,混淆矩阵、百分比的混淆矩阵、召回矩阵、精准矩阵、F1矩阵:
- 混淆矩阵是计数,百分比的混淆矩阵是占比
- 召回矩阵是,每行的和是1,每行代表真实类别数,占比就是召回
- 精准矩阵是,每列的和是1,每列代表预测列表数,占比就是精准
- F1矩阵是按照 2PR/(P+R),注意为0的情况,需要补0,使用np.divide(a, b, out=np.zeros_like(a), where=(b != 0))
代码如下:
# 横坐标是真实类别数,纵坐标是预测类别数 cf_matrix = confusion_matrix(y_true, y_pred) figure, axes = plt.subplots(2, 2, figsize=(16*1.25, 16)) # 混淆矩阵 ax = sns.heatmap(cf_matrix, annot=True, fmt='g', ax=axes[0][0], cmap='Blues') ax.title.set_text("Confusion Matrix") ax.set_xlabel("y_pred") ax.set_ylabel("y_true") # plt.savefig(csv_path.replace(".csv", "_cf_matrix.png")) # plt.show() # 混淆矩阵 - 百分比 cf_matrix = confusion_matrix(y_true, y_pred) ax = sns.heatmap(cf_matrix / np.sum(cf_matrix), annot=True, ax=axes[0][1], fmt='.2%', cmap='Blues') ax.title.set_text("Confusion Matrix (percent)") ax.set_xlabel("y_pred") ax.set_ylabel("y_true") # plt.savefig(csv_path.replace(".csv", "_cf_matrix_p.png")) # plt.show() # 召回矩阵,行和为1 sum_true = np.expand_dims(np.sum(cf_matrix, axis=1), axis=1) precision_matrix = cf_matrix / sum_true ax = sns.heatmap(precision_matrix, annot=True, fmt='.2%', ax=axes[1][0], cmap='Blues') ax.title.set_text("Precision Matrix") ax.set_xlabel("y_pred") ax.set_ylabel("y_true") # plt.savefig(csv_path.replace(".csv", "_recall.png")) # plt.show() # 精准矩阵,列和为1 sum_pred = np.expand_dims(np.sum(cf_matrix, axis=0), axis=0) recall_matrix = cf_matrix / sum_pred ax = sns.heatmap(recall_matrix, annot=True, fmt='.2%', ax=axes[1][1], cmap='Blues') ax.title.set_text("Recall Matrix") ax.set_xlabel("y_pred") ax.set_ylabel("y_true") # plt.savefig(csv_path.replace(".csv", "_precision.png")) # plt.show() # 绘制4张图 plt.autoscale(enable=False) plt.savefig(csv_path.replace(".csv", "_all.png"), bbox_inches='tight', pad_inches=0.2) plt.show() # F1矩阵 a = 2 * precision_matrix * recall_matrix b = precision_matrix + recall_matrix f1_matrix = np.divide(a, b, out=np.zeros_like(a), where=(b != 0)) ax = sns.heatmap(f1_matrix, annot=True, fmt='.2%', cmap='Blues') ax.title.set_text("F1 Matrix") ax.set_xlabel("y_pred") ax.set_ylabel("y_true") plt.savefig(csv_path.replace(".csv", "_f1.png")) plt.show()
输出混淆矩阵、混淆矩阵(百分比)、召回矩阵、精准矩阵:
F1 Score:
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