code: def initialize_from_ckpt(ckpt_dir, hparams):
    
    model_dir = hparams.get("model_dir", None)
    already_has_ckpt = (
        model_dir and tf.train.latest_checkpoint(model_dir) is not None)
    if already_has_ckpt:
      return
  
    tf.logging.info("Checkpoint dir: %s", ckpt_dir)
    reader = tf.contrib.framework.load_checkpoint(ckpt_dir)
    variable_map = {}
    for var in tf.contrib.framework.get_trainable_variables():
      var_name = var.name.split(":")[0]
      if reader.has_tensor(var_name):
        tf.logging.info("Loading variable from checkpoint: %s", var_name)
        variable_map[var_name] = var
      else:
        tf.logging.info("Cannot find variable in checkpoint, skipping: %s",
                        var_name)
    tf.train.init_from_checkpoint(ckpt_dir, variable_map)
docs: Initialize variables from given directory.