title: finding accuracy of tensorflow model
body: <p>I was trying to find the accuracy after training this simple linear model with sigmoid function: </p>
  
  <pre><code>import numpy as np
  import tensorflow as tf
  import _pickle as cPickle
  
  with open("var_x.txt", "rb") as fp:   # Unpickling
      var_x = cPickle.load(fp)
  
  with open("var_y.txt", "rb") as fp:   # Unpickling
      var_y = cPickle.load(fp)
  
  with open("var_x_test.txt", "rb") as fp:   # Unpickling
      var_x_test = cPickle.load(fp)
  
  with open("var_y_test.txt", "rb") as fp:   # Unpickling
      var_y_test = cPickle.load(fp)
  
  def model_fn(features, labels, mode):
    # Build a linear model and predict values
    W = tf.get_variable("W", [4], dtype=tf.float64)
    b = tf.get_variable("b", [1], dtype=tf.float64)
    y = tf.sigmoid( tf.reduce_sum(W*features['x']) + b)
    if mode == tf.estimator.ModeKeys.PREDICT:
      return tf.estimator.EstimatorSpec(mode=mode, predictions=y)
  
    loss = tf.reduce_sum(tf.square(y - labels))
  
    global_step = tf.train.get_global_step()
    optimizer = tf.train.GradientDescentOptimizer(0.01)
    train = tf.group(optimizer.minimize(loss),
                     tf.assign_add(global_step, 1))
  
    return tf.estimator.EstimatorSpec(
        mode=mode,
        predictions=y,
        loss=loss,
        train_op=train)
  
  estimator = tf.estimator.Estimator(model_fn=model_fn)
  
  x_train = np.array(var_x)
  y_train = np.array(var_y)
  x_test = np.array(var_x_test)
  y_test = np.array(var_y_test)
  
  input_fn = tf.estimator.inputs.numpy_input_fn(
      {"x": x_train}, y_train, batch_size=4, num_epochs=60, shuffle=True)
  
  estimator.train(input_fn=input_fn, steps=1000)
  
  test_input_fn= tf.estimator.inputs.numpy_input_fn(
      x ={"x":np.array(x_test)},
      y=np.array(y_test),
      num_epochs=1,
      shuffle=False
      )
  
  accuracy_score = estimator.evaluate(input_fn=test_input_fn["accuracy"])
  
  print(accuracy_score)
  </code></pre>
  
  <p>But the dictionary doesn't have an "accuracy" key. How do I find it? Also, how do I use tensorboard to track the accuracy after each step?</p>
  
  <p>Thank you in advance, the tensorflow tutorial is very bad at explaining.</p>