How to convert a Python list of lists to a 2D numpy array for sklearn.preprocessing
I currently have a list which contains all of my input for an sklearn classifier. Each element in that list is a list of features, where each element represents a song in my dataset. I need to convert this structure to a 2D numpy array so I can scale my data via sklearn's preprocessing. This is proving to be very difficult. y =  all_feats =  for song in data: mfccs_in_song = song oned_mfccs_in_song =  for frame in mfccs_in_song: for m in frame: oned_mfccs_in_song.append(m) all_feats.append(oned_mfccs_in_song) label = song[-1] y.append(label) Long story short, all_feats is that list of lists. It has a length of 600. How can I convert this to a numpy array for preprocessing? I have tried numerous things, including simply all_feats = np.array(all_feats), however that does not work.
That error suggests that all_feats may not have sublists of the same size. Take a look at its contents, and once you figure out what's the right length for the sublists, and how to prune the extra elements out, you can run all_feats = np.array(all_feats) and it should work! Take a look at the answers in this link for more explanation.
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