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    "# Logistic Regression in TensorFlow\n",
    "\n",
    "Credits: Forked from [TensorFlow-Examples](https://github.com/aymericdamien/TensorFlow-Examples) by Aymeric Damien\n",
    "\n",
    "## Setup\n",
    "\n",
    "Refer to the [setup instructions](http://nbviewer.ipython.org/github/donnemartin/data-science-ipython-notebooks/blob/master/deep-learning/tensor-flow-examples/Setup_TensorFlow.md)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Extracting /tmp/data/train-images-idx3-ubyte.gz\n",
      "Extracting /tmp/data/train-labels-idx1-ubyte.gz\n",
      "Extracting /tmp/data/t10k-images-idx3-ubyte.gz\n",
      "Extracting /tmp/data/t10k-labels-idx1-ubyte.gz\n"
     ]
    }
   ],
   "source": [
    "# Import MINST data\n",
    "import input_data\n",
    "mnist = input_data.read_data_sets(\"/tmp/data/\", one_hot=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "import tensorflow as tf"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Parameters\n",
    "learning_rate = 0.01\n",
    "training_epochs = 25\n",
    "batch_size = 100\n",
    "display_step = 1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# tf Graph Input\n",
    "x = tf.placeholder(\"float\", [None, 784]) # mnist data image of shape 28*28=784\n",
    "y = tf.placeholder(\"float\", [None, 10]) # 0-9 digits recognition => 10 classes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Create model\n",
    "\n",
    "# Set model weights\n",
    "W = tf.Variable(tf.zeros([784, 10]))\n",
    "b = tf.Variable(tf.zeros([10]))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Construct model\n",
    "activation = tf.nn.softmax(tf.matmul(x, W) + b) # Softmax"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Minimize error using cross entropy\n",
    "# Cross entropy\n",
    "cost = -tf.reduce_sum(y*tf.log(activation)) \n",
    "# Gradient Descent\n",
    "optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost) "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Initializing the variables\n",
    "init = tf.initialize_all_variables()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Epoch: 0001 cost= 29.860479714\n",
      "Epoch: 0002 cost= 22.080549484\n",
      "Epoch: 0003 cost= 21.237104595\n",
      "Epoch: 0004 cost= 20.460196280\n",
      "Epoch: 0005 cost= 20.185128237\n",
      "Epoch: 0006 cost= 19.940297202\n",
      "Epoch: 0007 cost= 19.645111119\n",
      "Epoch: 0008 cost= 19.507218031\n",
      "Epoch: 0009 cost= 19.389794492\n",
      "Epoch: 0010 cost= 19.177005816\n",
      "Epoch: 0011 cost= 19.082493615\n",
      "Epoch: 0012 cost= 19.072873598\n",
      "Epoch: 0013 cost= 18.938005402\n",
      "Epoch: 0014 cost= 18.891806430\n",
      "Epoch: 0015 cost= 18.839480221\n",
      "Epoch: 0016 cost= 18.769349510\n",
      "Epoch: 0017 cost= 18.590865587\n",
      "Epoch: 0018 cost= 18.623413677\n",
      "Epoch: 0019 cost= 18.546149085\n",
      "Epoch: 0020 cost= 18.432274895\n",
      "Epoch: 0021 cost= 18.358189004\n",
      "Epoch: 0022 cost= 18.380014628\n",
      "Epoch: 0023 cost= 18.499993471\n",
      "Epoch: 0024 cost= 18.386477311\n",
      "Epoch: 0025 cost= 18.258080609\n",
      "Optimization Finished!\n",
      "Accuracy: 0.9048\n"
     ]
    }
   ],
   "source": [
    "# Launch the graph\n",
    "with tf.Session() as sess:\n",
    "    sess.run(init)\n",
    "\n",
    "    # Training cycle\n",
    "    for epoch in range(training_epochs):\n",
    "        avg_cost = 0.\n",
    "        total_batch = int(mnist.train.num_examples/batch_size)\n",
    "        # Loop over all batches\n",
    "        for i in range(total_batch):\n",
    "            batch_xs, batch_ys = mnist.train.next_batch(batch_size)\n",
    "            # Fit training using batch data\n",
    "            sess.run(optimizer, feed_dict={x: batch_xs, y: batch_ys})\n",
    "            # Compute average loss\n",
    "            avg_cost += sess.run(cost, feed_dict={x: batch_xs, y: batch_ys})/total_batch\n",
    "        # Display logs per epoch step\n",
    "        if epoch % display_step == 0:\n",
    "            print \"Epoch:\", '%04d' % (epoch+1), \"cost=\", \"{:.9f}\".format(avg_cost)\n",
    "\n",
    "    print \"Optimization Finished!\"\n",
    "\n",
    "    # Test model\n",
    "    correct_prediction = tf.equal(tf.argmax(activation, 1), tf.argmax(y, 1))\n",
    "    # Calculate accuracy\n",
    "    accuracy = tf.reduce_mean(tf.cast(correct_prediction, \"float\"))\n",
    "    print \"Accuracy:\", accuracy.eval({x: mnist.test.images, y: mnist.test.labels})"
   ]
  }
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