I have an existing pandas dataframe below:

```
   id  time  c  d
0   1     1  2  3
1   1     3  1  6
2   2     2  3  2
3   2     3  8  6

```

I also have values stored in a list such as:

```
list = [0.4, 0.6]

```

I want to create a new column in the existing dateframe and assign each list element in the first row for each group (id) such as:

```
   id  time  c  d  new_col
0   1     1  2  3  0.4
1   1     3  1  6
2   2     2  3  2  0.6
3   2     3  8  6

```