How about this:

```
def masscenter(ser):
print(df.loc[ser.index])
return 0
rol = df.price.rolling(window=2)
rol.apply(masscenter, raw=False)
```

It uses the rolling logic to get subsets from an arbitrary column. The raw=False option provides you with index values for those subsets (which are given to you as Series), then you use those index values to get multi-column slices from your original DataFrame.