2_fullyconnected.ipynb

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    "Deep Learning\n",
    "=============\n",
    "\n",
    "Assignment 2\n",
    "------------\n",
    "\n",
    "Previously in `1_notmnist.ipynb`, we created a pickle with formatted datasets for training, development and testing on the [notMNIST dataset](http://yaroslavvb.blogspot.com/2011/09/notmnist-dataset.html).\n",
    "\n",
    "The goal of this assignment is to progressively train deeper and more accurate models using TensorFlow."
   ]
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   "source": [
    "# These are all the modules we'll be using later. Make sure you can import them\n",
    "# before proceeding further.\n",
    "from __future__ import print_function\n",
    "import numpy as np\n",
    "import tensorflow as tf\n",
    "from six.moves import cPickle as pickle\n",
    "from six.moves import range\n",
    "import math"
   ]
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   "source": [
    "First reload the data we generated in `1_notmnist.ipynb`."
   ]
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     "text": [
      "Training set (200000, 28, 28) (200000,)\n",
      "Validation set (10000, 28, 28) (10000,)\n",
      "Test set (10000, 28, 28) (10000,)\n"
     ]
    }
   ],
   "source": [
    "pickle_file = 'notMNIST.pickle'\n",
    "\n",
    "with open(pickle_file, 'rb') as f:\n",
    "    save = pickle.load(f)\n",
    "    train_dataset = save['train_dataset']\n",
    "    train_labels = save['train_labels']\n",
    "    valid_dataset = save['valid_dataset']\n",
    "    valid_labels = save['valid_labels']\n",
    "    test_dataset = save['test_dataset']\n",
    "    test_labels = save['test_labels']\n",
    "    del save  # hint to help gc free up memory\n",
    "    print('Training set', train_dataset.shape, train_labels.shape)\n",
    "    print('Validation set', valid_dataset.shape, valid_labels.shape)\n",
    "    print('Test set', test_dataset.shape, test_labels.shape)"
   ]
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   "source": [
    "Reformat into a shape that's more adapted to the models we're going to train:\n",
    "- data as a flat matrix,\n",
    "- labels as float 1-hot encodings."
   ]
  },
  {
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     "text": [
      "Training set (200000, 784) (200000, 10)\n",
      "Validation set (10000, 784) (10000, 10)\n",
      "Test set (10000, 784) (10000, 10)\n"
     ]
    }
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   "source": [
    "image_size = 28\n",
    "num_labels = 10\n",
    "\n",
    "def reformat(dataset, labels):\n",
    "    dataset = dataset.reshape((-1, image_size * image_size)).astype(np.float32)\n",
    "    # Map 0 to [1.0, 0.0, 0.0 ...], 1 to [0.0, 1.0, 0.0 ...]\n",
    "    labels = (np.arange(num_labels) == labels[:,None]).astype(np.float32)\n",
    "    return dataset, labels\n",
    "train_dataset, train_labels = reformat(train_dataset, train_labels)\n",
    "valid_dataset, valid_labels = reformat(valid_dataset, valid_labels)\n",
    "test_dataset, test_labels = reformat(test_dataset, test_labels)\n",
    "print('Training set', train_dataset.shape, train_labels.shape)\n",
    "print('Validation set', valid_dataset.shape, valid_labels.shape)\n",
    "print('Test set', test_dataset.shape, test_labels.shape)"
   ]
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   "source": [
    "We're first going to train a multinomial logistic regression using simple gradient descent.\n",
    "\n",
    "TensorFlow works like this:\n",
    "* First you describe the computation that you want to see performed: what the inputs, the variables, and the operations look like. These get created as nodes over a computation graph. This description is all contained within the block below:\n",
    "\n",
    "      with graph.as_default():\n",
    "          ...\n",
    "\n",
    "* Then you can run the operations on this graph as many times as you want by calling `session.run()`, providing it outputs to fetch from the graph that get returned. This runtime operation is all contained in the block below:\n",
    "\n",
    "      with tf.Session(graph=graph) as session:\n",
    "          ...\n",
    "\n",
    "Let's load all the data into TensorFlow and build the computation graph corresponding to our training:"
   ]
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   "source": [
    "# With gradient descent training, even this much data is prohibitive.\n",
    "# Subset the training data for faster turnaround.\n",
    "train_subset = 10000\n",
    "\n",
    "graph = tf.Graph()\n",
    "with graph.as_default():\n",
    "\n",
    "    # Input data.\n",
    "    # Load the training, validation and test data into constants that are\n",
    "    # attached to the graph.\n",
    "    tf_train_dataset = tf.constant(train_dataset[:train_subset, :])\n",
    "    tf_train_labels = tf.constant(train_labels[:train_subset])\n",
    "    tf_valid_dataset = tf.constant(valid_dataset)\n",
    "    tf_test_dataset = tf.constant(test_dataset)\n",
    "  \n",
    "    # Variables.\n",
    "    # These are the parameters that we are going to be training. The weight\n",
    "    # matrix will be initialized using random valued following a (truncated)\n",
    "    # normal distribution. The biases get initialized to zero.\n",
    "    weights = tf.Variable(\n",
    "        tf.truncated_normal([image_size * image_size, num_labels]))\n",
    "    biases = tf.Variable(tf.zeros([num_labels]))\n",
    "  \n",
    "    # Training computation.\n",
    "    # We multiply the inputs with the weight matrix, and add biases. We compute\n",
    "    # the softmax and cross-entropy (it's one operation in TensorFlow, because\n",
    "    # it's very common, and it can be optimized). We take the average of this\n",
    "    # cross-entropy across all training examples: that's our loss.\n",
    "    logits = tf.matmul(tf_train_dataset, weights) + biases\n",
    "    loss = tf.reduce_mean(\n",
    "        tf.nn.softmax_cross_entropy_with_logits(logits, tf_train_labels))\n",
    "  \n",
    "    # Optimizer.\n",
    "    # We are going to find the minimum of this loss using gradient descent.\n",
    "    optimizer = tf.train.GradientDescentOptimizer(0.5).minimize(loss)\n",
    "  \n",
    "    # Predictions for the training, validation, and test data.\n",
    "    # These are not part of training, but merely here so that we can report\n",
    "    # accuracy figures as we train.\n",
    "    train_prediction = tf.nn.softmax(logits)\n",
    "    valid_prediction = tf.nn.softmax(\n",
    "        tf.matmul(tf_valid_dataset, weights) + biases)\n",
    "    test_prediction = tf.nn.softmax(tf.matmul(tf_test_dataset, weights) + biases)"
   ]
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   "source": [
    "Let's run this computation and iterate:"
   ]
  },
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     "text": [
      "Initialized\n",
      "Loss at step 0: 16.585104\n",
      "Training accuracy: 11.8%\n",
      "Validation accuracy: 14.0%\n",
      "Loss at step 100: 2.364428\n",
      "Training accuracy: 71.2%\n",
      "Validation accuracy: 70.3%\n",
      "Loss at step 200: 1.881092\n",
      "Training accuracy: 74.5%\n",
      "Validation accuracy: 73.1%\n",
      "Loss at step 300: 1.619438\n",
      "Training accuracy: 76.0%\n",
      "Validation accuracy: 73.8%\n",
      "Loss at step 400: 1.442997\n",
      "Training accuracy: 77.1%\n",
      "Validation accuracy: 73.9%\n",
      "Loss at step 500: 1.313934\n",
      "Training accuracy: 77.9%\n",
      "Validation accuracy: 74.1%\n",
      "Loss at step 600: 1.214786\n",
      "Training accuracy: 78.7%\n",
      "Validation accuracy: 74.1%\n",
      "Loss at step 700: 1.135448\n",
      "Training accuracy: 79.2%\n",
      "Validation accuracy: 74.3%\n",
      "Loss at step 800: 1.070023\n",
      "Training accuracy: 79.6%\n",
      "Validation accuracy: 74.6%\n",
      "Test accuracy: 82.9%\n"
     ]
    }
   ],
   "source": [
    "num_steps = 801\n",
    "\n",
    "def accuracy(predictions, labels):\n",
    "    return (100.0 * np.sum(np.argmax(predictions, 1) == np.argmax(labels, 1))\n",
    "          / predictions.shape[0])\n",
    "\n",
    "with tf.Session(graph=graph) as session:\n",
    "    # This is a one-time operation which ensures the parameters get initialized as\n",
    "    # we described in the graph: random weights for the matrix, zeros for the\n",
    "    # biases.\n",
    "    tf.initialize_all_variables().run()\n",
    "    print('Initialized')\n",
    "    for step in range(num_steps):\n",
    "        # Run the computations. We tell .run() that we want to run the optimizer,\n",
    "        # and get the loss value and the training predictions returned as numpy\n",
    "        # arrays.\n",
    "        _, l, predictions = session.run([optimizer, loss, train_prediction])\n",
    "        if (step % 100 == 0):\n",
    "            print('Loss at step %d: %f' % (step, l))\n",
    "            print('Training accuracy: %.1f%%' % accuracy(\n",
    "                predictions, train_labels[:train_subset, :]))\n",
    "            # Calling .eval() on valid_prediction is basically like calling run(), but\n",
    "            # just to get that one numpy array. Note that it recomputes all its graph\n",
    "            # dependencies.\n",
    "            print('Validation accuracy: %.1f%%' % accuracy(\n",
    "                valid_prediction.eval(), valid_labels))\n",
    "    print('Test accuracy: %.1f%%' % accuracy(test_prediction.eval(), test_labels))"
   ]
  },
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   "cell_type": "markdown",
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   "source": [
    "Let's now switch to stochastic gradient descent training instead, which is much faster.\n",
    "\n",
    "The graph will be similar, except that instead of holding all the training data into a constant node, we create a `Placeholder` node which will be fed actual data at every call of `session.run()`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
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   "source": [
    "batch_size = 128\n",
    "\n",
    "graph = tf.Graph()\n",
    "with graph.as_default():\n",
    "\n",
    "    # Input data. For the training data, we use a placeholder that will be fed\n",
    "    # at run time with a training minibatch.\n",
    "    tf_train_dataset = tf.placeholder(tf.float32,\n",
    "                                    shape=(batch_size, image_size * image_size))\n",
    "    tf_train_labels = tf.placeholder(tf.float32, shape=(batch_size, num_labels))\n",
    "    tf_valid_dataset = tf.constant(valid_dataset)\n",
    "    tf_test_dataset = tf.constant(test_dataset)\n",
    "  \n",
    "    # Variables.\n",
    "    weights = tf.Variable(\n",
    "        tf.truncated_normal([image_size * image_size, num_labels]))\n",
    "    biases = tf.Variable(tf.zeros([num_labels]))\n",
    "  \n",
    "    # Training computation.\n",
    "    logits = tf.matmul(tf_train_dataset, weights) + biases\n",
    "    loss = tf.reduce_mean(\n",
    "        tf.nn.softmax_cross_entropy_with_logits(logits, tf_train_labels))\n",
    "  \n",
    "    # Optimizer.\n",
    "    optimizer = tf.train.GradientDescentOptimizer(0.5).minimize(loss)\n",
    "  \n",
    "    # Predictions for the training, validation, and test data.\n",
    "    train_prediction = tf.nn.softmax(logits)\n",
    "    valid_prediction = tf.nn.softmax(\n",
    "        tf.matmul(tf_valid_dataset, weights) + biases)\n",
    "    test_prediction = tf.nn.softmax(tf.matmul(tf_test_dataset, weights) + biases)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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   "source": [
    "Let's run it:"
   ]
  },
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   "outputs": [
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     "text": [
      "Initialized\n",
      "Minibatch loss at step 0: 16.034298\n",
      "Minibatch accuracy: 10.9%\n",
      "Validation accuracy: 10.1%\n",
      "Minibatch loss at step 500: 1.290899\n",
      "Minibatch accuracy: 78.9%\n",
      "Validation accuracy: 75.7%\n",
      "Minibatch loss at step 1000: 1.279335\n",
      "Minibatch accuracy: 77.3%\n",
      "Validation accuracy: 76.8%\n",
      "Minibatch loss at step 1500: 0.833913\n",
      "Minibatch accuracy: 79.7%\n",
      "Validation accuracy: 76.5%\n",
      "Minibatch loss at step 2000: 0.858698\n",
      "Minibatch accuracy: 84.4%\n",
      "Validation accuracy: 77.8%\n",
      "Minibatch loss at step 2500: 0.837036\n",
      "Minibatch accuracy: 78.9%\n",
      "Validation accuracy: 78.2%\n",
      "Minibatch loss at step 3000: 1.082029\n",
      "Minibatch accuracy: 79.7%\n",
      "Validation accuracy: 78.6%\n",
      "Test accuracy: 86.6%\n"
     ]
    }
   ],
   "source": [
    "num_steps = 3001\n",
    "\n",
    "with tf.Session(graph=graph) as session:\n",
    "    tf.initialize_all_variables().run()\n",
    "    print(\"Initialized\")\n",
    "    for step in range(num_steps):\n",
    "        # Pick an offset within the training data, which has been randomized.\n",
    "        # Note: we could use better randomization across epochs.\n",
    "        offset = (step * batch_size) % (train_labels.shape[0] - batch_size)\n",
    "        # Generate a minibatch.\n",
    "        batch_data = train_dataset[offset:(offset + batch_size), :]\n",
    "        batch_labels = train_labels[offset:(offset + batch_size), :]\n",
    "        # Prepare a dictionary telling the session where to feed the minibatch.\n",
    "        # The key of the dictionary is the placeholder node of the graph to be fed,\n",
    "        # and the value is the numpy array to feed to it.\n",
    "        feed_dict = {tf_train_dataset : batch_data, tf_train_labels : batch_labels}\n",
    "        _, l, predictions = session.run(\n",
    "            [optimizer, loss, train_prediction], feed_dict=feed_dict)\n",
    "        if (step % 500 == 0):\n",
    "            print(\"Minibatch loss at step %d: %f\" % (step, l))\n",
    "            print(\"Minibatch accuracy: %.1f%%\" % accuracy(predictions, batch_labels))\n",
    "            print(\"Validation accuracy: %.1f%%\" % accuracy(\n",
    "                valid_prediction.eval(), valid_labels))\n",
    "    print(\"Test accuracy: %.1f%%\" % accuracy(test_prediction.eval(), test_labels))"
   ]
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   "source": [
    "---\n",
    "Problem\n",
    "-------\n",
    "\n",
    "Turn the logistic regression example with SGD into a 1-hidden layer neural network with rectified linear units [nn.relu()](https://www.tensorflow.org/versions/r0.7/api_docs/python/nn.html#relu) and 1024 hidden nodes. This model should improve your validation / test accuracy.\n",
    "\n",
    "---"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": true
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   "outputs": [],
   "source": [
    "IMAGE_PIXELS = image_size * image_size"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
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   "source": [
    "batch_size = 128\n",
    "hidden_units = 1024\n",
    "\n",
    "graph = tf.Graph()\n",
    "with graph.as_default():\n",
    "    # Input data. For the training data, we use a placeholder that will be fed\n",
    "    # at run time with a training minibatch.\n",
    "    tf_train_dataset = tf.placeholder(tf.float32, shape=(batch_size,\n",
    "                                                         IMAGE_PIXELS))\n",
    "    tf_train_labels = labels_placeholder = tf.placeholder(tf.float32, shape=(batch_size, num_labels))\n",
    "    tf_valid_dataset = tf.constant(valid_dataset)\n",
    "    tf_test_dataset = tf.constant(test_dataset)\n",
    "    \n",
    "    \n",
    "    with tf.name_scope('hidden1'):\n",
    "        weights = tf.Variable(\n",
    "            tf.truncated_normal([image_size * image_size, hidden_units],\n",
    "                            stddev=1.0 / math.sqrt(float(IMAGE_PIXELS))),\n",
    "            name='weights')\n",
    "        biases = tf.Variable(tf.zeros([hidden_units]),\n",
    "                         name='biases')\n",
    "        hidden = tf.nn.relu(tf.matmul(tf_train_dataset, weights) + biases)\n",
    "        valid1 = tf.nn.relu(tf.matmul(tf_valid_dataset, weights) + biases)\n",
    "        test1 = tf.nn.relu(tf.matmul(tf_test_dataset, weights) + biases)\n",
    "        \n",
    "    with tf.name_scope('softmax_linear'):\n",
    "        weights = tf.Variable(\n",
    "            tf.truncated_normal([hidden_units, num_labels],\n",
    "                            stddev=1.0/ math.sqrt(float(IMAGE_PIXELS))),\n",
    "            name = 'weights')\n",
    "        biases = tf.Variable(tf.zeros([num_labels]))\n",
    "        logits = tf.matmul(hidden, weights) + biases\n",
    "        valid2 = tf.matmul(valid1, weights) + biases\n",
    "        test2 = tf.matmul(test1, weights) + biases\n",
    "    \n",
    "    loss = tf.reduce_mean(\n",
    "        tf.nn.softmax_cross_entropy_with_logits(logits, tf_train_labels))\n",
    "  \n",
    "    # Optimizer.\n",
    "    optimizer = tf.train.GradientDescentOptimizer(0.5).minimize(loss)\n",
    "  \n",
    "    # Predictions for the training, validation, and test data.\n",
    "    train_prediction = tf.nn.softmax(logits)\n",
    "    valid_prediction = tf.nn.softmax(valid2)\n",
    "    test_prediction = tf.nn.softmax(test2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Initialized\n",
      "Minibatch loss at step 0: 2.274965\n",
      "Minibatch accuracy: 13.3%\n",
      "Validation accuracy: 42.2%\n",
      "Minibatch loss at step 500: 0.379432\n",
      "Minibatch accuracy: 88.3%\n",
      "Validation accuracy: 85.9%\n",
      "Minibatch loss at step 1000: 0.453212\n",
      "Minibatch accuracy: 87.5%\n",
      "Validation accuracy: 86.9%\n",
      "Minibatch loss at step 1500: 0.284394\n",
      "Minibatch accuracy: 91.4%\n",
      "Validation accuracy: 87.8%\n",
      "Minibatch loss at step 2000: 0.285409\n",
      "Minibatch accuracy: 94.5%\n",
      "Validation accuracy: 87.8%\n",
      "Minibatch loss at step 2500: 0.285027\n",
      "Minibatch accuracy: 91.4%\n",
      "Validation accuracy: 88.3%\n",
      "Minibatch loss at step 3000: 0.362755\n",
      "Minibatch accuracy: 88.3%\n",
      "Validation accuracy: 88.0%\n",
      "Test accuracy: 94.3%\n"
     ]
    }
   ],
   "source": [
    "num_steps = 3001\n",
    "\n",
    "with tf.Session(graph=graph) as session:\n",
    "    tf.initialize_all_variables().run()\n",
    "    print(\"Initialized\")\n",
    "    for step in range(num_steps):\n",
    "        # Pick an offset within the training data, which has been randomized.\n",
    "        # Note: we could use better randomization across epochs.\n",
    "        offset = (step * batch_size) % (train_labels.shape[0] - batch_size)\n",
    "        # Generate a minibatch.\n",
    "        batch_data = train_dataset[offset:(offset + batch_size), :]\n",
    "        batch_labels = train_labels[offset:(offset + batch_size), :]\n",
    "        # Prepare a dictionary telling the session where to feed the minibatch.\n",
    "        # The key of the dictionary is the placeholder node of the graph to be fed,\n",
    "        # and the value is the numpy array to feed to it.\n",
    "        feed_dict = {tf_train_dataset : batch_data, tf_train_labels : batch_labels}\n",
    "        _, l, predictions = session.run([optimizer, loss, train_prediction], feed_dict=feed_dict)\n",
    "        if (step % 500 == 0):\n",
    "            print(\"Minibatch loss at step %d: %f\" % (step, l))\n",
    "            print(\"Minibatch accuracy: %.1f%%\" % accuracy(predictions, batch_labels))\n",
    "            print(\"Validation accuracy: %.1f%%\" % accuracy(\n",
    "                valid_prediction.eval(), valid_labels))\n",
    "    print(\"Test accuracy: %.1f%%\" % accuracy(test_prediction.eval(), test_labels))"
   ]
  }
 ],
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