Use `np.unique(y_train)` to view all labels in `y_train`
Use `set(y_train)` to view unique labels if `y_train` is a list
Use `print(y_train.shape)` to check the label array size
Use `print(y_train[:])` to display all labels if the array is small
Use `pd.Series(y_train).value_counts()` to see label counts
Use `np.bincount(y_train)` if labels are non-negative integers
Use `print(sorted(np.unique(y_train)))` to see labels in order