Signature:
df.to_csv(
    path_or_buf: 'FilePath | WriteBuffer[bytes] | WriteBuffer[str] | None' = None,
    sep: 'str' = ',',
    na_rep: 'str' = '',
    float_format: 'str | None' = None,
    columns: 'Sequence[Hashable] | None' = None,
    header: 'bool_t | list[str]' = True,
    index: 'bool_t' = True,
    index_label: 'IndexLabel | None' = None,
    mode: 'str' = 'w',
    encoding: 'str | None' = None,
    compression: 'CompressionOptions' = 'infer',
    quoting: 'int | None' = None,
    quotechar: 'str' = '"',
    line_terminator: 'str | None' = None,
    chunksize: 'int | None' = None,
    date_format: 'str | None' = None,
    doublequote: 'bool_t' = True,
    escapechar: 'str | None' = None,
    decimal: 'str' = '.',
    errors: 'str' = 'strict',
    storage_options: 'StorageOptions' = None,
) -> 'str | None'
Docstring:
Write object to a comma-separated values (csv) file.

Parameters
----------
path_or_buf : str, path object, file-like object, or None, default None
    String, path object (implementing os.PathLike[str]), or file-like
    object implementing a write() function. If None, the result is
    returned as a string. If a non-binary file object is passed, it should
    be opened with `newline=''`, disabling universal newlines. If a binary
    file object is passed, `mode` might need to contain a `'b'`.

    .. versionchanged:: 1.2.0

       Support for binary file objects was introduced.

sep : str, default ','
    String of length 1. Field delimiter for the output file.
na_rep : str, default ''
    Missing data representation.
float_format : str, default None
    Format string for floating point numbers.
columns : sequence, optional
    Columns to write.
header : bool or list of str, default True
    Write out the column names. If a list of strings is given it is
    assumed to be aliases for the column names.
index : bool, default True
    Write row names (index).
index_label : str or sequence, or False, default None
    Column label for index column(s) if desired. If None is given, and
    `header` and `index` are True, then the index names are used. A
    sequence should be given if the object uses MultiIndex. If
    False do not print fields for index names. Use index_label=False
    for easier importing in R.
mode : str
    Python write mode, default 'w'.
encoding : str, optional
    A string representing the encoding to use in the output file,
    defaults to 'utf-8'. `encoding` is not supported if `path_or_buf`
    is a non-binary file object.
compression : str or dict, default 'infer'
    For on-the-fly compression of the output data. If 'infer' and '%s'
    path-like, then detect compression from the following extensions: '.gz',
    '.bz2', '.zip', '.xz', or '.zst' (otherwise no compression). Set to
    ``None`` for no compression. Can also be a dict with key ``'method'`` set
    to one of {``'zip'``, ``'gzip'``, ``'bz2'``, ``'zstd'``} and other
    key-value pairs are forwarded to ``zipfile.ZipFile``, ``gzip.GzipFile``,
    ``bz2.BZ2File``, or ``zstandard.ZstdDecompressor``, respectively. As an
    example, the following could be passed for faster compression and to create
    a reproducible gzip archive:
    ``compression={'method': 'gzip', 'compresslevel': 1, 'mtime': 1}``.

    .. versionchanged:: 1.0.0

       May now be a dict with key 'method' as compression mode
       and other entries as additional compression options if
       compression mode is 'zip'.

    .. versionchanged:: 1.1.0

       Passing compression options as keys in dict is
       supported for compression modes 'gzip', 'bz2', 'zstd', and 'zip'.

    .. versionchanged:: 1.2.0

        Compression is supported for binary file objects.

    .. versionchanged:: 1.2.0

        Previous versions forwarded dict entries for 'gzip' to
        `gzip.open` instead of `gzip.GzipFile` which prevented
        setting `mtime`.

quoting : optional constant from csv module
    Defaults to csv.QUOTE_MINIMAL. If you have set a `float_format`
    then floats are converted to strings and thus csv.QUOTE_NONNUMERIC
    will treat them as non-numeric.
quotechar : str, default '\"'
    String of length 1. Character used to quote fields.
line_terminator : str, optional
    The newline character or character sequence to use in the output
    file. Defaults to `os.linesep`, which depends on the OS in which
    this method is called ('\\n' for linux, '\\r\\n' for Windows, i.e.).
chunksize : int or None
    Rows to write at a time.
date_format : str, default None
    Format string for datetime objects.
doublequote : bool, default True
    Control quoting of `quotechar` inside a field.
escapechar : str, default None
    String of length 1. Character used to escape `sep` and `quotechar`
    when appropriate.
decimal : str, default '.'
    Character recognized as decimal separator. E.g. use ',' for
    European data.
errors : str, default 'strict'
    Specifies how encoding and decoding errors are to be handled.
    See the errors argument for :func:`open` for a full list
    of options.

    .. versionadded:: 1.1.0

storage_options : dict, optional
    Extra options that make sense for a particular storage connection, e.g.
    host, port, username, password, etc. For HTTP(S) URLs the key-value pairs
    are forwarded to ``urllib`` as header options. For other URLs (e.g.
    starting with "s3://", and "gcs://") the key-value pairs are forwarded to
    ``fsspec``. Please see ``fsspec`` and ``urllib`` for more details.

    .. versionadded:: 1.2.0

Returns
-------
None or str
    If path_or_buf is None, returns the resulting csv format as a
    string. Otherwise returns None.

See Also
--------
read_csv : Load a CSV file into a DataFrame.
to_excel : Write DataFrame to an Excel file.

Examples
--------
>>> df = pd.DataFrame({'name': ['Raphael', 'Donatello'],
...                    'mask': ['red', 'purple'],
...                    'weapon': ['sai', 'bo staff']})
>>> df.to_csv(index=False)
'name,mask,weapon\nRaphael,red,sai\nDonatello,purple,bo staff\n'

Create 'out.zip' containing 'out.csv'

>>> compression_opts = dict(method='zip',
...                         archive_name='out.csv')  # doctest: +SKIP
>>> df.to_csv('out.zip', index=False,
...           compression=compression_opts)  # doctest: +SKIP

To write a csv file to a new folder or nested folder you will first
need to create it using either Pathlib or os:

>>> from pathlib import Path  # doctest: +SKIP
>>> filepath = Path('folder/subfolder/out.csv')  # doctest: +SKIP
>>> filepath.parent.mkdir(parents=True, exist_ok=True)  # doctest: +SKIP
>>> df.to_csv(filepath)  # doctest: +SKIP

>>> import os  # doctest: +SKIP
>>> os.makedirs('folder/subfolder', exist_ok=True)  # doctest: +SKIP
>>> df.to_csv('folder/subfolder/out.csv')  # doctest: +SKIP
File:      ~/miniconda3/envs/pystudy/lib/python3.10/site-packages/pandas/core/generic.py
Type:      method