code: def from_df(cls, df):
          
          return cls(df['M1'], df['M2'], df['P'],
                     ecc=df['ecc'], mean_anomaly=df['mean_anomaly'],
                     obsx=df['obsx'], obsy=df['obsy'], obsz=df['obsz'])
docs: Creates an OrbitPopulation from a DataFrame.
  
          :param df:
              :class:`pandas.DataFrame` object.  Must contain the following
              columns: ``['M1','M2','P','ecc','mean_anomaly','obsx','obsy','obsz']``,
              i.e., as what is accessed via :attr:`OrbitPopulation.dataframe`.
  
          :return:
              :class:`OrbitPopulation`.