给定以下数据集:
from pandas import DataFrame
Data = {
'a1': [,0,,0.01,0,0.03,0.01,0.01,,0,0,0,0.01,0.01,0,0.01,0,0.01,0.01,0.01,0,,,,0,0,0.01,0.01,0.02,0.03,0],
'a2': [,,,,,,,,,,,,,,,,,,,,,,,0,0,,,0,,,],
'a3': [,0,0.02,,,0,0.01,0.03,0,0.01,0.01,0.02,,,,,,,,0.01,0.01,0,0