Calculate Wildman-Crippen logP
    Wildman S., Crippen G., Prediction of Physicochemical Parameters by Atomic
    Contribution, J. Chem. Inf. Model. 39 (1999) 868-873

def wcparams(mol, type_):
    """
    Calculate Wildman-Crippen logP
    Wildman S., Crippen G., Prediction of Physicochemical Parameters by Atomic
    Contribution, J. Chem. Inf. Model. 39 (1999) 868-873
    """
    try:
        assign_wctype(mol)
    except:
        return "N/A"
    scores = []
    for i, atom in mol.atoms_iter():
        scores.append(float(DATA[type_][atom.wctype]))
        if atom.H_count:
            if atom.symbol == "C":
                scores.append(DATA[type_]["H1"] * atom.H_count)
            elif atom.symbol == "N":
                scores.append(DATA[type_]["H3"] * atom.H_count)
            elif atom.wctype == "O2a":
                scores.append(DATA[type_]["H4"] * atom.H_count)
            else:
                scores.append(DATA[type_]["H2"] * atom.H_count)
    return round(sum(scores), 2)