python-forensics-handbook/pyforhandbook/ch01_essentials/csv_example.py

"""Example for writing datasets into CSV files.

Demonstrates source datasets comprised of lists of dictionaries
and lists of lists as separate functions. Example data is
provided in line and will generate two identical CSVs as output.

Example Usage:

    ``$ python csv_example.py``

References:

* https://docs.python.org/3/library/csv.html
* https://docs.python.org/3/library/os.html


List of dictionaries to CSV
===========================

Example ``data`` variable:

::

    [
        {'name': 'apple', 'quantity': 10, 'location': 'VT'},
        {'name': 'orange', 'quantity': 5, 'location': 'FL'}
    ]

This first function shows an example of writing a list containing
multiple dictionaries to a CSV file. You can optionally provide
an ordered list of headers to filter what rows to show, or let the
function use the keys of the first dictionary in the list to
generate the header information. The latter option may produce
a new order each iteration and is not preferred if you can
determine the headers in advance.

.. literalinclude:: ../pyforhandbook/ch01_essentials/csv_example.py
    :pyobject: write_csv_dicts

List of ordered lists to CSV
============================

Example ``data`` variable:

::

    [
        ['name', 'quantity', 'location'],
        ['apple', 10, 'VT'],
        ['orange', 5, 'FL']
    ]

This function shows an example of writing a list containing
multiple lists to a CSV file. You can optionally provide
an ordered list of headers, or let the function use the values
of the first element in the list to generate the header
information. Unlike the dictionary option, you cannot filter
column data by adjusting the provided headers, you must write all
columns to the CSV.

.. literalinclude:: ../pyforhandbook/ch01_essentials/csv_example.py
    :pyobject: write_csv_lists


Docstring References
====================
"""

import csv

"""
Copyright 2019 Chapin Bryce

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use, copy,
modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
"""

__author__ = "Chapin Bryce"
__date__ = 20190527
__license__ = "MIT Copyright 2019 Chapin Bryce"
__desc__ = """Sample script to write to CSV files."""
__docs__ = [
    "https://docs.python.org/3/library/csv.html",
    "https://docs.python.org/3/library/os.html",
]


def write_csv_dicts(outfile, data, headers=None):
    """Writes a list of dictionaries to a CSV file.

    Arguments:
        outfile (str): Path to output file
        data (list): List of dictionaries to write to file
        headers (list): Header row to use. If empty, will use the
            first dictionary in the `data` list.

    Example:
        >>> list_of_dicts = [
        >>>     {'name': 'apple', 'quantity': 10, 'location': 'VT'},
        >>>     {'name': 'orange', 'quantity': 5, 'location': 'FL'}
        >>> ]
        >>> write_csv_dicts('dict_test.csv', list_of_dicts)
    """

    if not headers:
        # Use the first line of data
        headers = [str(x) for x in data[0].keys()]

    with open(outfile, "w", newline="") as open_file:
        # Write only provided headers, ignore others
        csv_file = csv.DictWriter(open_file, headers, extrasaction="ignore")
        csv_file.writeheader()
        csv_file.writerows(data)


def write_csv_lists(outfile, data, headers=None):
    """Writes a list of lists to a CSV file.

    Arguments:
        outfile (str): Path to output file
        data (list): List of lists to write to file
        headers (list): Header row to use. If empty, will use the
            first list in the `data` list.

    Examples:
        >>> fields = ['name', 'quantity', 'location']
        >>> list_of_lists = [
        >>>     ['apple', 10, 'VT'],
        >>>     ['orange', 5, 'FL']
        >>> ]
        >>> write_csv_lists('list_test.csv', list_of_lists, headers=fields)
    """

    with open(outfile, "w", newline="") as open_file:
        # Write only provided headers, ignore others
        csv_file = csv.writer(open_file)
        for count, entry in enumerate(data):
            if count == 0 and headers:
                # If headers are defined, write them, otherwise
                # continue as they will be written anyways
                csv_file.writerow(headers)
            csv_file.writerow(entry)


if __name__ == "__main__":
    sample_dict_data = [
        {"id": "0", "city": "Boston", "state": "MA", "country": "USA"},
        {"id": "1", "city": "New York", "state": "NY", "country": "USA"},
        {"id": "2", "city": "Washington", "state": "DC", "country": "USA"},
    ]

    write_csv_dicts("dict_test.csv", sample_dict_data)

    header_row = ["id", "city", "state", "country"]
    sample_list_data = [
        ["0", "Boston", "MA", "USA"],
        ["1", "New York", "NY", "USA"],
        ["2", "Washington", "DC", "USA"],
    ]

    write_csv_lists("list_test.csv", sample_list_data, headers=header_row)