Use a dictionary comprehension while iterating via a groupby object
{name: dict(zip(g['Col Y'], g['Sum'])) for name, g in df.groupby('Col X')}{'A': {'a': 3, 'b': 2, 'c': 1}, 'B': {'p': 5, 'q': 6, 'r': 7}}If you insisted on using to_dict somewhere, you could do something like this:
s = df.set_index(['Col X', 'Col Y']).Sum{k: s.xs(k).to_dict() for k in s.index.levels[0]}{'A': {'a': 3, 'b': 2, 'c': 1}, 'B': {'p': 5, 'q': 6, 'r': 7}}Keep in mind, that the to_dict method is just using some comprehension under the hood. If you have a special use case that requires something more than what the orient options provide for... there is no shame in constructing your own comprehension.
