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

Activate the HDFStore.


path_or_buf : the path (string) or HDFStore object

key : string

indentifier for the group in the store

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


Read-only; no data can be modified.


Write; a new file is created (an existing file with the same name would be deleted).


Append; an existing file is opened for reading and writing, and if the file does not exist it is created.


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

complevel : int, 1-9, default 0

If a complib is specified compression will be applied where possible

complib : {‘zlib’, ‘bzip2’, ‘lzo’, ‘blosc’, None}, default None

If complevel is > 0 apply compression to objects written in the store wherever possible

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.