Use `len(classes_)` instead of  `len(set(y_true))` (#5275)
Use `len(classes_)` instead of  `len(set(y_true))` (#5275)

* Use n_classes instead of len(set(y_true))

Signed-off-by: harupy <3b81b8b110f2244bdbf0f43efa472935c395c613@users.noreply.github.com>

* fix attribute

Signed-off-by: harupy <3b81b8b110f2244bdbf0f43efa472935c395c613@users.noreply.github.com>

* use classes_

Signed-off-by: harupy <3b81b8b110f2244bdbf0f43efa472935c395c613@users.noreply.github.com>

* handle meta estimator

Signed-off-by: harupy <3b81b8b110f2244bdbf0f43efa472935c395c613@users.noreply.github.com>

* address comment

Signed-off-by: harupy <3b81b8b110f2244bdbf0f43efa472935c395c613@users.noreply.github.com>

* fix

Signed-off-by: harupy <3b81b8b110f2244bdbf0f43efa472935c395c613@users.noreply.github.com>
mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow,mlflow/mlflow