Pandas mixed mode dataframe cannot serialize in hdf5?
In Pandas, it seems that I cannot store a mixed-type dataframe:
store = HDFStore('play.h5')
df = DataFrame([{'a': 1, 'b': 'hello'}, {'a': 5, 'b': 'world'}])
store.put('df', df, table=True, compression='zlib')
This gives Exception: Cannot currently store mixed-type DataFrame objects in Table format
Is this due to some inherent limitation of Pandas, or is it just future-friendly? It looks like HDFStore
it won't be very useful with this limitation, since a lot of the data will be of mixed types.
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The table format stores all data in record form, i.e. all values are stored in one column. There is an alternative table format that can be used (one column per DataFrame column) but I haven't implemented it yet. Basically the table format is designed to support queries
Mixed DataFrame can be preserved if you use table = False. More work on these features would be welcome.
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