# pandas.Panel.to_hdf

`Panel.``to_hdf`(path_or_buf, key, **kwargs)

  Write the contained data to an HDF5 file using HDFStore.

  Parameters:

  path_or_buf : the path (string) or HDFStore object

  key : string

  > identifier for the group in the store

  mode : optional, {‘a’, ‘w’, ‘r+’}, default ‘a’

  > `'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+'`

  >   It is similar to `'a'`, but the file must already exist.

  format : ‘fixed(f)|table(t)’, default is ‘fixed’

  > fixed(f) : Fixed format

  >   Fast writing/reading. Not-appendable, nor searchable

  > table(t) : Table format

  >   Write as a PyTables Table structure which may perform worse but allow more flexible operations like searching / selecting subsets of the data

  append : boolean, default False

  > For Table formats, append the input data to the existing

  data_columns : list of columns, or True, default None

  > 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. See here.

  > Applicable only to format=’table’.

  complevel : int, 0-9, default None

  > Specifies a compression level for data. A value of 0 disables compression.

  complib : {‘zlib’, ‘lzo’, ‘bzip2’, ‘blosc’}, default ‘zlib’

  > 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.

  fletcher32 : bool, default False

  > If applying compression use the fletcher32 checksum

  dropna : boolean, default False.

  > If true, ALL nan rows will not be written to store.

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