通过熊猫中相同数据帧的切片索引设置数据帧的列不起作用

Question

I'm trying to set values of column for some rows of dataframe based on index of dataframe view. This does not work as expected. What are altrenatives?

i tried following code:

df=pd.DataFrame({'a':[1,2,3]})
dfb=df[df.a>1]
df['c']=np.nan
df.loc[dfb[dfb.a>2].index]['c']=10
df.loc[dfb[dfb.a>2].index]

expected that c column of df.loc[dfb[dfb.a>2].index] would be 10. it is still nan

Answer 1

尝试将df.loc[dfb[dfb.a>2].index]['c']=10更改为df.loc[dfb[dfb.a>2].index,'c']=10 。