替换熊猫中某年之前的所有细胞

Question

我有一个数据集，其中2001年之前的任何日期均无效。我想用NaT替换日期在2001年之前的每个实例。

我试图做这样的事情，但这只能用于一列，而且是不正确的...

public GameObject sm; //assigned in-editor
public SpatialMapping smm;

void Start()
{
    smm = sm.GetComponent<SpatialMapping>();
}

void ChangeColor(Color newColor) //this is called in an omitted part of the script that assigns newColor
{
    //what I WANT to do:
    Material newMat = smm.getSurfaceMaterial();
    newMat.color = newColor;
    smm.SetSurfaceMaterial(newMat);

}

Answer 1

df[df['Delivery Date'].dt.year == 2001]['Delivery Date']=np.nan

Answer 2

df.loc[df['Delivery Date'].dt.year <= 2001, 'Delivery Date'] = np.nan

查看关于.loc的{​​{3}}