variables.py 文件源码

def create_global_step(graph=None):
  """Create global step tensor in graph.

  Args:
    graph: The graph in which to create the global step. If missing, use default
        graph.

  Returns:
    Global step tensor.

  Raises:
    ValueError: if global step key is already defined.
  """
  graph = ops.get_default_graph() if graph is None else graph
  if get_global_step(graph) is not None:
    raise ValueError('"global_step" already exists.')
  # Create in proper graph and base name_scope.
  with graph.as_default() as g, g.name_scope(None):
    collections = [ops.GraphKeys.VARIABLES, ops.GraphKeys.GLOBAL_STEP]
    return variable(ops.GraphKeys.GLOBAL_STEP, shape=[], dtype=dtypes.int64,
                    initializer=init_ops.zeros_initializer, trainable=False,
                    collections=collections)