I have a pandas df that looks like this:

```
beta
0 matrix([[1], [2], [3]])
1 matrix([[2], [3], [4]])
2 matrix([[0], [0], [0]])
:
999 matrix([[2], [1], [3]])
```

And I want to access the first entry of `df['beta']`

, idealy either a list or a np array that looks like:
`[1, 2, 0, ..., 2]`

What I have tried so far:

Convert the series to a list of lists

```
b_t = list(df['beta_t'].apply(lambda x: x.flatten().tolist()[0]))
b_t = [row[0] for row in b_t]
```

This works, but it takes a while in large datasets.

I also tried:

```
b_t = list(df['beta_t'].apply(lambda x: np.array(x.flatten()[0])))
```

but this results in a series of series and I don't know how to continue from here.

Any suggestions on how I should improve my codes? Thanks in advance!

I believe you need:

Or: