Tensorflow试图使用未初始化值AUC/AUC/AUC/false-positives

Question

我在训练一个CNN用图像分类。由于我的数据集有限，我正在使用转移学习。基本上，我使用的是Google在其retrain示例（https://www.tensorflow.org/tutorials/image_retraining）中证明的经过预先训练的网络。

模型运行良好，精度很高。但是我的数据集是高度不平衡的，这意味着准确性不是判断模型性能的最佳指标。

通过研究不同的解决方案，一些人建议改变采样方法或使用的性能指标。我选择晚一点去。

Tensorflow提供了一个很好的度量标准，包括AUC、精度、召回等

现在，这是重新训练模型的代码： https://github.com/tensorflow/tensorflow/blob/master/tensorflow/examples/image_retraining/retrain.py

我在add_evaluation_step(result_tensor, ground_truth_tensor)函数中添加以下内容：

  with tf.name_scope('AUC'):
    with tf.name_scope('prediction'):
        prediction = tf.argmax(result_tensor, 1)
    with tf.name_scope('AUC'):
        auc_value = tf.metrics.auc(tf.argmax(ground_truth_tensor, 1), prediction, curve='ROC')


  tf.summary.scalar('accuracy', evaluation_step)
  tf.summary.scalar('AUC', auc_value)

但我有个错误：

Traceback (most recent call last): File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/examples/image_retraining/retrain.py", line 1135, in tf.app.run(main=main, argv=[sys.argv[0]] + unparsed) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/platform/app.py", line 44, in run _sys.exit(main(_sys.argv[:1] + flags_passthrough)) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/examples/image_retraining/retrain.py", line 911, in main ground_truth_input: train_ground_truth}) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/client/session.py", line 767, in run run_metadata_ptr) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/client/session.py", line 965, in _run feed_dict_string, options, run_metadata) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/client/session.py", line 1015, in _do_run target_list, options, run_metadata) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/client/session.py", line 1035, in _do_call raise type(e)(node_def, op, message) tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value AUC/AUC/auc/false_positives
[[Node: AUC/AUC/auc/false_positives/read = IdentityT=DT_FLOAT, _class=["loc:@AUC/AUC/auc/false_positives"], _device="/job:localhost/replica:0/task:0/cpu:0"]]

Caused by op u'AUC/AUC/auc/false_positives/read', defined at: File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/examples/image_retraining/retrain.py", line 1135, in tf.app.run(main=main, argv=[sys.argv[0]] + unparsed) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/platform/app.py", line 44, in run _sys.exit(main(_sys.argv[:1] + flags_passthrough)) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/examples/image_retraining/retrain.py", line 874, in main final_tensor, ground_truth_input) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/examples/image_retraining/retrain.py", line 806, in add_evaluation_step auc_value, update_op = tf.metrics.auc(tf.argmax(ground_truth_tensor, 1), prediction, curve='ROC') File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/ops/metrics_impl.py", line 555, in auc labels, predictions, thresholds, weights) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/ops/metrics_impl.py", line 473, in _confusion_matrix_at_thresholds false_p = _create_local('false_positives', shape=[num_thresholds]) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/ops/metrics_impl.py", line 177, in _create_local validate_shape=validate_shape) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/ops/variables.py", line 226, in init expected_shape=expected_shape) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/ops/variables.py", line 344, in _init_from_args self._snapshot = array_ops.identity(self._variable, name="read") File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/ops/gen_array_ops.py", line 1490, in identity result = _op_def_lib.apply_op("Identity", input=input, name=name) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/framework/op_def_library.py", line 768, in apply_op op_def=op_def) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/framework/ops.py", line 2402, in create_op original_op=self._default_original_op, op_def=op_def) File "/home/user_2/tensorflow/bazel-bin/tensorflow/examples/image_retraining/retrain.runfiles/org_tensorflow/tensorflow/python/framework/ops.py", line 1264, in init self._traceback = _extract_stack()

FailedPreconditionError (see above for traceback): Attempting to use uninitialized value AUC/AUC/auc/false_positives [[Node: AUC/AUC/auc/false_positives/read = IdentityT=DT_FLOAT, _class=["loc:@AUC/AUC/auc/false_positives"], _device="/job:localhost/replica:0/task:0/cpu:0"]]

但我不明白这是为什么，主要是因为我有：

init = tf.global_variables_initializer()
sess.run(init)