Pandas DataFrame: to_hdf() function

DataFrame - to_hdf() function

The to_hdf() function is used to write the contained data to an HDF5 file using HDFStore.


DataFrame.to_hdf(self, path_or_buf, key, **kwargs)


Name Description Type/Default Value Required / Optional
path_or_buf      File path or HDFStore object. str or pandas.HDFStore Required
key        Identifier for the group in the store. str Required
mode   Mode to open file:
  • 'w': write, a new file is created (an existing file with the same name would be deleted).
  • 'a': append, an existing file is opened for reading and writing, and if the file does not exist it is created.
  • ‘r+’: similar to 'a', but the file must already exist.
{'a', 'w', 'r+'}
Default Value: ‘a’
format   Possible values:
  • 'fixed': Fixed format. Fast writing/reading. Not-appendable, nor searchable.
  • 'table': Table format. Write as a PyTables Table structure which may perform worse but allow more flexible operations like searching / selecting subsets of the data.
{‘fixed’, ‘table’}
Default Value: ‘fixed’
append    For Table formats, append the input data to the existing. bool
Default Value: False
data_columns   List of columns to create as indexed data columns for on-disk queries, or True to use all columns. By default only the axes of the object are indexed.  list of columns
Default Value: True
complevel   Specifies a compression level for data. A value of 0 disables compression. {0-9} Optional
complib   Specifies the compression library to be used. As of v0.20.2 these additional compressors for Blosc are supported (default if no compressor specified: ‘blosc:blosclz’): {‘blosc:blosclz’, ‘blosc:lz4’, ‘blosc:lz4hc’, ‘blosc:snappy’, ‘blosc:zlib’, ‘blosc:zstd’}. Specifying a compression library which is not available issues a ValueError. {‘zlib’, ‘lzo’, ‘bzip2’, ‘blosc’}
Default Value: ‘zlib’
fletcher32   If applying compression use the fletcher32 checksum. bool
Default Value: False
dropna   If true, ALL nan rows will not be written to store. bool
Default Value: False
errors   Specifies how encoding and decoding errors are to be handled. See the errors argument for open() for a full list of options. str
Default Value: ‘strict’


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