how to convert a Series of arrays into a single matrix in pandas/numpy?

Question

I somehow got a pandas.Series which contains a bunch of arrays in it, as the s in the code below.

data = [[1,2,3],[2,3,4],[3,4,5],[2,3,4],[3,4,5],[2,3,4],         [3,4,5],[2,3,4],[3,4,5],[2,3,4],[3,4,5]] s = pd.Series(data = data) s.shape # output ---> (11L,) # try to convert s to matrix sm = s.as_matrix() # but... sm.shape # output ---> (11L,) 

How can I convert the s into a matrix with shape (11,3)? Thanks!

Answer 1

Another way is to extract the values of your series and use numpy.stack on them.

np.stack(s.values) 

PS. I've run into similar situations often.

Answer 2

If, for some reason, you have found yourself with that abomination of a Series, getting it back into the sort of matrix or array you want is straightforward:

In [16]: s Out[16]: 0     [1, 2, 3] 1     [2, 3, 4] 2     [3, 4, 5] 3     [2, 3, 4] 4     [3, 4, 5] 5     [2, 3, 4] 6     [3, 4, 5] 7     [2, 3, 4] 8     [3, 4, 5] 9     [2, 3, 4] 10    [3, 4, 5] dtype: object  In [17]: sm = np.array(s.tolist())  In [18]: sm Out[18]: array([[1, 2, 3],        [2, 3, 4],        [3, 4, 5],        [2, 3, 4],        [3, 4, 5],        [2, 3, 4],        [3, 4, 5],        [2, 3, 4],        [3, 4, 5],        [2, 3, 4],        [3, 4, 5]])  In [19]: sm.shape Out[19]: (11, 3) 

But unless it's something you can't change, having that Series makes little sense to begin with.