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arsho/Stackoverflow_Answer.md

Created January 2, 2022 19:46
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  1. arsho created this gist Jan 2, 2022.
    37 changes: 37 additions & 0 deletions Stackoverflow_Answer.md
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    ### Four numbers each from -1 to 1 that sum up to 1

    You can use Python's [combination with replacement method](https://docs.python.org/3.1/library/itertools.html?highlight=combinations#itertools.combinations_with_replacement).

    ```
    from itertools import combinations_with_replacement
    import csv
    def get_four_numbers(target_sum=100):
    result = []
    ar = list(range(-100, 101, 1))
    for quadruplet in combinations_with_replacement(ar, 4):
    if sum(quadruplet) == target_sum:
    result.append([i / 100.0 for i in quadruplet])
    return result
    if __name__ == "__main__":
    with open("output.csv", "w") as output_file:
    csv_writer = csv.writer(output_file)
    csv_writer.writerows(get_four_numbers())
    ```

    **Output from `output.csv` (truncated due to filesize):**

    ```
    -1.0,0.0,1.0,1.0
    -1.0,0.01,0.99,1.0
    -1.0,0.02,0.98,1.0
    -1.0,0.02,0.99,0.99
    -1.0,0.03,0.97,1.0
    -1.0,0.03,0.98,0.99
    -1.0,0.04,0.96,1.0
    .....
    ```

    **References:**
    - [combination with replacement method](https://docs.python.org/3.1/library/itertools.html?highlight=combinations#itertools.combinations_with_replacement)