def up(f, c):
    """Find the positive values in the series.

    Parameters
    ----------
    f : pandas.DataFrame
        Dataframe containing the column ``c``.
    c : str
        Name of the column in the dataframe ``f``.

    Returns
    -------
    new_column : pandas.Series (bool)
        The array containing the new feature.

    """
    new_column = f[c] > 0
    return new_column
