def fillBy(self,df,na_feature,features):#features 包含了na_feature
ref=df[features]
_known=ref[na_feature.notnull()]
_unknown=ref[na_feature.isnull()]
_Y=_known[na_feature].values
_X=_known.drop(na_feature,axis=1).values
_P=_unknown.drop(na_feature,axis=1).values
rfr=RandomForestRegressor(random_state=0,n_estimators=2000)
rfr.fig(_X,_Y)
predictna=rfr.predict(_P)
df.loc[na_feature.isnull(),na_feature]=predictna
