Pandas 表格转为树

def split_to_tree_structure():

    from collections import defaultdict

    import pandas as pd

    df = pd.DataFrame([['A', 'a', 'a1'],

                       ['A', 'a', 'a2'],

                       ['A', 'b', 'b1'],

                       ['A', 'b', 'b2'],

                       ['A', 'c', 'c1'],

                       ['A', 'c', 'c2']],

                      columns=['col1', 'col2', 'col3'])

    d = defaultdict(lambda: defaultdict(list))

    for row in df.itertuples():

        d[row[1]][row[2]].append(row[3])

    print(d)

if __name__ == '__main__':

    split_to_tree_structure()

    print('end!')