How to convert ndarray to array?

I'm using pandas.Series and np.ndarray.

The code is like this

>>> t array([[ 0., 0., 0.], [ 0., 0., 0.], [ 0., 0., 0.]]) >>> pandas.Series(t) Exception: Data must be 1-dimensional >>> 

And I trie to convert it into 1-dimensional array:

>>> tt = t.reshape((1,-1)) >>> tt array([[ 0., 0., 0., 0., 0., 0., 0., 0., 0.]]) 

tt is still multi-dimensional since there are double '['.

So how do I get a really convert ndarray into array?

After searching, it says they are the same. However in my situation, they are not working the same.

3 Answers

An alternative is to use np.ravel:

>>> np.zeros((3,3)).ravel() array([ 0., 0., 0., 0., 0., 0., 0., 0., 0.]) 

The importance of ravel over flatten is ravel only copies data if necessary and usually returns a view, while flatten will always return a copy of the data.

To use reshape to flatten the array:

tt = t.reshape(-1) 

Use .flatten:

>>> np.zeros((3,3)) array([[ 0., 0., 0.], [ 0., 0., 0.], [ 0., 0., 0.]]) >>> _.flatten() array([ 0., 0., 0., 0., 0., 0., 0., 0., 0.]) 

EDIT: As pointed out, this returns a copy of the input in every case. To avoid the copy, use .ravel as suggested by @Ophion.

tt = array([[ 0., 0., 0., 0., 0., 0., 0., 0., 0.]]) oneDvector = tt.A1 

This is the only approach which solved the problem of double brackets, that is conversion to 1D array that nd matrix.