def makeSymmetricDF(df):
  """
  Makes the dataframe symmetric if uncalculated values are np.nan.

  Parameters
  ----------
  df: pd.DataFrame
    index is same a columns
  
  Returns
  -------
  pd.DataFrame
  """
  df_result = df.fillna(0)
  df_result += df_result.T
  features = list(df_result.columns)
  df_result.loc[features, features] *= 0.5  # count diagonal once
  return df_result