matplotlib坐标原点不重合

用matplotlib画图时会遇到原点不重合在左下角的情况

fig,ax=plt.subplots(figsize=(8,5))
    ax.plot(range(1,13),error_train,label="Train")
    ax.plot(range(1,13),error_cv,label="Cross Validation",color="green")
    ax.legend()
    plt.xlabel("Number of training examples")
    plt.ylabel('error')
    plt.title('Learning curve of linear regression')
    plt.show()

只需要添加两行代码即可

plt.ylim(bottom=0)
plt.xlim(left=0)