python metric.auc的运用

def plot_auc(y_test,y_pred):
    fpr, tpr, thread = metrics.roc_curve(np.array(y_test), np.array(y_pred))
    x=metrics.auc(fpr, tpr)
    plt.title("ROC curve of %s (AUC = %.4f)" % ('lightgbm', x))
    plt.xlabel("False Positive Rate")
    plt.ylabel("True Positive Rate")
    plt.plot(fpr,tpr)  
    plt.show()