using 

```
import pandas as pd
import numpy as np

```

Given this Dataframe, 

```
df = pd.DataFrame(np.array([[1, 2, 3],
                             [4, 5, 6],
                             [7, 8, 9],
                             [10, 11, 12],
                             [13, 14, 15],
                             [16, 17, 18],
                             [19, 20, 21]
                             ]),
                   columns=['a', 'b', 'c'])

Out[1]: 
    a   b   c
0   1   2   3
1   4   5   6
2   7   8   9
3  10  11  12
4  13  14  15
5  16  17  18
6  19  20  21

```

I want to re order and put back in place the rows 2 to 5,

```
2   7   8   9
3  10  11  12
4  13  14  15
5  16  17  18

```

If the order within the subset is `[2,0,1,3]` the desired result is,

```
Out[2]: 
    a   b   c
0   1   2   3
1   4   5   6
4  13  14  15
2   7   8   9
3  10  11  12
5  16  17  18
6  19  20  21

```

(I need to do this for different subsets in different orders. This is just an example.)

My attempt,

My subset,

```
idx = [2,3,4,5]
idx2 = np.array(idx)

```

The new order

```
i = [2,0,1,3]

```

if I do, 

```
df.iloc[idx].reindex(idx2[i])

```

I do get the subset in the right order, then, I thought the following should work,

```
df.iloc[idx] = df.iloc[idx].reindex(idx2[i]).reset_index(drop=True)

```

but it does not, because on both sides they need to match the indices. So, I would need either to set an offset on the index, which would be a bit nasty. Or make this operation to ignore the indices on the right hand side.
Any idea?