def get_y_chars(self):

        _max = max([max(s.values._get_cache()) for s in self._series])
        return len(str(int(_max)))
estimate nb of chars for y axis
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/tablib-0.10.0/tablib/packages/openpyxl/chart.py/Chart.get_y_chars