code: def _zscore(a):
      
      assert a.ndim > 1, 'a must have more than one dimensions'
      zscore = scipy.stats.zscore(a, axis=0)
      zscore[:, np.logical_not(np.all(np.isfinite(zscore), axis=0))] = 0
      return zscore
docs: Calculating z-score of data on the first axis.
          If the numbers in any column are all equal, scipy.stats.zscore
          will return NaN for this column. We shall correct them all to
          be zeros.
  
      Parameters
      ----------
      a: numpy array
  
      Returns
      -------
      zscore: numpy array
          The z-scores of input "a", with any columns including non-finite
          numbers replaced by all zeros.