DOC: description of read_csv parameter chunksize does not mention its value is number of lines per chunk

[tpaxman]

Pandas version checks

• I have checked that the issue still exists on the latest versions of the docs on main here

Location of the documentation

https://pandas.pydata.org/docs/dev/reference/api/pandas.read_csv.html

Documentation problem

Current description of chunksize only mentions that TextFileReader will be the return value but does not state that its value is the number of lines per chunk:

chunksize : int, optional
    Return ``TextFileReader`` object for iteration.
    See the `IO Tools docs
    <https://pandas.pydata.org/pandas-docs/stable/io.html#io-chunking>`_
    for more information on ``iterator`` and ``chunksize``.

Suggested fix for documentation

Add a sentence to the description to specify that it represents number of lines per chunk.

[tpaxman]

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