How to allow "half windows" in biopython?
You can choose between a window_size of 20 for sequences longer than 20 AAs, and the length of the sequence for those shorter::

seq = "CYGTGAVYLLGLGIGGFS"
window_length = min(len(seq), 20)

full_sequence_analysis = ProteinAnalysis(seq)
kyte_window = full_sequence_analysis.protein_scale(kyte, window_length, edge)