def predictions_for_df(df, inferrer):
  """Returns df with column that's the activations for each sequence.

  Args:
    df: DataFrame with columns 'sequence' and 'sequence_name'.
    inferrer: inferrer.

  Returns:
    pd.DataFrame with columns 'sequence_name', 'predicted_label', and
    'predictions'. 'predictions' has type np.ndarray, whose shape depends on
    inferrer.activation_type.
  """
  working_df = df.copy()
  working_df['predictions'] = inferrer.get_activations(
      working_df.sequence.values).tolist()
  return working_df