Merge pull request #738 from rbberger/pylammps_thermo_style_fix

            self.lmp.eval("fy[%d]" % self.index))

class variable_set:

    def __init__(self, name, variable_dict):

        self._name = name

        array_pattern = re.compile(r"(?P<arr>.+)\[(?P<index>[0-9]+)\]")

        for key, value in variable_dict.items():

            m = array_pattern.match(key)

            if m:

                g = m.groupdict()

                varname = g['arr']

                idx = int(g['index'])

                if varname not in self.__dict__:

                    self.__dict__[varname] = {}

                self.__dict__[varname][idx] = value

            else:

                self.__dict__[key] = value

    def __str__(self):

        return "{}({})".format(self._name, ','.join(["{}={}".format(k, self.__dict__[k]) for k in self.__dict__.keys() if not k.startswith('_')]))

    def __repr__(self):

        return self.__str__()

def get_thermo_data(output):

    """ traverse output of runs and extract thermo data columns """

    if isinstance(output, str):

        elif line.startswith("Loop time of "):

            in_run = False

            columns = None

            thermo_data = namedtuple('ThermoData', list(current_run.keys()))(*list(current_run.values()))

            thermo_data = variable_set('ThermoData', current_run)

            r = {'thermo' : thermo_data }

            runs.append(namedtuple('Run', list(r.keys()))(*list(r.values())))

        elif in_run and len(columns) > 0: