You can specify a python write mode in the pandas to_csv function. For append it is 'a'.

In your case:

df.to_csv('my_csv.csv', mode='a', header=False)

The default mode is 'w'.

If the file initially might be missing, you can make sure the header is printed at the first write using this variation:

output_path='my_csv.csv'
df.to_csv(output_path, mode='a', header=not os.path.exists(output_path))
Answer from tlingf on Stack Overflow
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Pandas
pandas.pydata.org › docs › reference › api › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas 3.0.3 documentation
Write object to a comma-separated values (csv) file. ... 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 ...
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GitHub
github.com › dask › dask › issues › 9088
to_csv save mode default & options · Issue #9088 · dask/dask
May 14, 2022 - The default to_csv save mode is "wt", but the docs say "w", so that's a little typo to fix. pandas has different to_csv write modes like w+, w, and a.
Author   dask
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Programiz
programiz.com › python-programming › pandas › methods › to_csv
Pandas to_csv() (With Examples)
import pandas as pd data = { 'Name': ['Alice', 'Bob', 'Charlie'], 'Age': [25, 30, 35], 'City': ['New York', 'San Francisco', 'Los Angeles'] } df = pd.DataFrame(data) # use to_csv() to write df to a CSV file df.to_csv('sample_data.csv') '' Output sample_data.csv: Name,Age,City Alice,25,New York Bob,30,San Francisco Charlie,35,Los Angeles '' ... df.to_csv(path_or_buf, sep=',', header=True, index=False, mode='w', encoding=None, quoting=None, line_terminator='\n')
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Note.nkmk.me
note.nkmk.me › home › python › pandas
pandas: Write DataFrame to CSV with to_csv() | note.nkmk.me
August 4, 2023 - You can write data from pandas.DataFrame and pandas.Series to CSV files using the to_csv() method. This method also allows appending to an existing CSV file. By altering the delimiter, the data can be ...
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Pandas
pandas.pydata.org › docs › dev › reference › api › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas documentation
The output can be written to a file path, file-like buffer, or returned as a string. ... 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’.
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Data Science Parichay
datascienceparichay.com › home › blog › pandas – append dataframe to existing csv
Pandas - Append dataframe to existing CSV - Data Science Parichay
March 27, 2021 - To append a dataframe row-wise to an existing CSV file, you can write the dataframe to the CSV file in append mode using the pandas to_csv() function.
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w3resource
w3resource.com › pandas › dataframe › dataframe-to_csv.php
Pandas DataFrame: to_csv() function - w3resource
August 19, 2022 - DataFrame.to_csv(self, path_or_buf=None, sep=', ', na_rep='', float_format=None, columns=None, header=True, index=True, index_label=None, mode='w', encoding=None, compression='infer', quoting=None, quotechar='"', line_terminator=None, chunksize=None, date_format=None, doublequote=True, escapechar=None, decimal='.') Parameters: Returns: None or str If path_or_buf is None, returns the resulting csv format as a string. Otherwise returns None. Example: Download the Pandas DataFrame Notebooks from here. PREV : DataFrame - to_pickle() function NEXT : DataFrame - to_hdf() function  ·
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DigitalOcean
digitalocean.com › community › tutorials › pandas-to_csv-convert-dataframe-to-csv
Pandas to_csv() - Convert DataFrame to CSV | DigitalOcean
August 3, 2022 - Pandas DataFrame to_csv() function converts DataFrame into CSV data. We can pass a file object to write the CSV data into a file. Otherwise, the CSV data is returned in the string format. The syntax of DataFrame to_csv() function is: def to_csv( self, path_or_buf=None, sep=",", na_rep="", ...
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Pandas
pandas.pydata.org › pandas-docs › version › 1.0.4 › reference › api › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas 1.0.4 documentation
Changed in version 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’. ... Defaults to csv.QUOTE_MINIMAL.
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Pandas
pandas.pydata.org › pandas-docs › version › 0.13.1 › generated › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas 0.13.1 documentation
Contributing to pandas · Release Notes · Enter search terms or a module, class or function name. DataFrame.to_csv(path_or_buf, sep=', ', na_rep='', float_format=None, cols=None, header=True, index=True, index_label=None, mode='w', nanRep=None, encoding=None, quoting=None, line_terminator='n', chunksize=None, tupleize_cols=False, date_format=None, **kwds)¶ ·
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Pandas
pandas.pydata.org › pandas-docs › version › 2.0 › reference › api › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas 2.0.3 documentation
Write object to a comma-separated values (csv) file. ... 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 ...
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GeeksforGeeks
geeksforgeeks.org › how-to-append-pandas-dataframe-to-existing-csv-file
How to Append Pandas DataFrame to Existing CSV File? - GeeksforGeeks
December 6, 2023 - Add Pandas DataFrame to an Existing CSV File. To achieve this, we can utilize the to_csv() function in Pandas with the 'a' parameter to write the DataFrame to the CSV file in append mode.
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Spark By {Examples}
sparkbyexamples.com › home › pandas › pandas write dataframe to csv
Pandas Write DataFrame to CSV - Spark By {Examples}
October 2, 2024 - By using pandas.DataFrame.to_csv() method you can write/save/export a pandas DataFrame to CSV File. By default to_csv() method export DataFrame to a CSV
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Net Informations
net-informations.com › ds › pd › tocsv.htm
How to Export Pandas DataFrame to a CSV File
In this example, we use mode='a' ... ensures that the column headers are not written again when appending to the file. To write a Pandas DataFrame to a CSV file, you can use the to_csv() method....
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Pandas
pandas.pydata.org › pandas-docs › version › 2.1 › reference › api › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas 2.1.4 documentation
Write object to a comma-separated values (csv) file. ... 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 ...
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Pandas
pandas.pydata.org › docs › reference › api › pandas.Series.to_csv.html
pandas.Series.to_csv — pandas 3.0.2 documentation - PyData |
Write object to a comma-separated values (csv) file. ... 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 ...
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Pandas
pandas.pydata.org › pandas-docs › version › 0.14.1 › generated › pandas.DataFrame.to_csv.html
pandas.DataFrame.to_csv — pandas 0.14.1 documentation
Contributing to pandas · Release Notes · Enter search terms or a module, class or function name. DataFrame.to_csv(*args, **kwargs)¶ · Write DataFrame to a comma-separated values (csv) file · index · modules | next | previous | pandas 0.14.1 documentation » ·
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Medium
medium.com › @robblatt › use-python-and-pandas-to-append-to-a-csv-503bf22670ce
Use Python and Pandas to Append to a CSV | by Rob Blatt | Medium
September 9, 2019 - # header = False will prevent the headers from being written to your file, which would come along with a Nan value for the row.# ----------------------------------------------------------------- # IF YOU CAME HERE VIA SEARCH, THIS IS THE CODE YOU ARE LOOKING FOR # -----------------------------------------------------------------df2.to_csv('test.csv', mode = 'a', header = False)# You're still reading?