def atom_fractions(atoms):
    r'''Calculates the atomic fractions of each element in a compound,
    given a dictionary of its atoms and their counts, in the format
    {symbol: count}.

    .. math::
        a_i =  \frac{n_i}{\sum_i n_i}

    Parameters
    ----------
    atoms : dict
        dictionary of counts of individual atoms, indexed by symbol with
        proper capitalization, [-]

    Returns
    -------
    afracs : dict
        dictionary of atomic fractions of individual atoms, indexed by symbol
        with proper capitalization, [-]

    Notes
    -----
    No actual data on the elements is used, so incorrect or custom compounds
    would not raise an error.

    Examples
    --------
    >>> atom_fractions({'H': 12, 'C': 20, 'O': 5})
    {'H': 0.32432432432432434, 'C': 0.5405405405405406, 'O': 0.13513513513513514}

    References
    ----------
    .. [1] RDKit: Open-source cheminformatics; http://www.rdkit.org
    '''
    count = sum(atoms.values())
    afracs = {}
    for i in atoms:
        afracs[i] = atoms[i]/count
    return afracs
def atom_fractions(atoms):
    r'''Calculates the atomic fractions of each element in a compound,
    given a dictionary of its atoms and their counts, in the format
    {symbol: count}.

    .. math::
        a_i =  \frac{n_i}{\sum_i n_i}

    Parameters
    ----------
    atoms : dict
        dictionary of counts of individual atoms, indexed by symbol with
        proper capitalization, [-]

    Returns
    -------
    afracs : dict
        dictionary of atomic fractions of individual atoms, indexed by symbol
        with proper capitalization, [-]

    Notes
    -----
    No actual data on the elements is used, so incorrect or custom compounds
    would not raise an error.

    Examples
    --------
    >>> atom_fractions({'H': 12, 'C': 20, 'O': 5})
    {'H': 0.32432432432432434, 'C': 0.5405405405405406, 'O': 0.13513513513513514}

    References
    ----------
    .. [1] RDKit: Open-source cheminformatics; http://www.rdkit.org
    '''
    count = sum(atoms.values())
    afracs = {}
    for i in atoms:
        afracs[i] = atoms[i]/count
    return afracs
def atom_fractions ( atoms ) : count = sum ( atoms . values ( ) ) afracs = { } for i in atoms : afracs [ i ] = atoms [ i ] / count return afracs
r'''Calculates the atomic fractions of each element in a compound,
    given a dictionary of its atoms and their counts, in the format
    {symbol: count}.

    .. math::
        a_i =  \frac{n_i}{\sum_i n_i}

    Parameters
    ----------
    atoms : dict
        dictionary of counts of individual atoms, indexed by symbol with
        proper capitalization, [-]

    Returns
    -------
    afracs : dict
        dictionary of atomic fractions of individual atoms, indexed by symbol
        with proper capitalization, [-]

    Notes
    -----
    No actual data on the elements is used, so incorrect or custom compounds
    would not raise an error.

    Examples
    --------
    >>> atom_fractions({'H': 12, 'C': 20, 'O': 5})
    {'H': 0.32432432432432434, 'C': 0.5405405405405406, 'O': 0.13513513513513514}

    References
    ----------
    .. [1] RDKit: Open-source cheminformatics; http://www.rdkit.org
r Calculates the atomic fractions of each element in a compound given a dictionary of its atoms and their counts in the format { symbol : count } .