Merge pull request #127 from AnEscapist/patch-6

Update 3.分类.md

docs/3.分类.md

@@ -256,7 +256,7 @@ Scikit-Learn 提供了一些函数去计算分类器的指标，包括准确率
 
 ```python
 >>> from sklearn.metrics import f1_score
->>> f1_score(y_train_5, y_pred)
+>>> f1_score(y_train_5, y_train_pred)
 0.78468208092485547
 ```