94-775, 95-865 Neural net handwritten digit recognition.ipynb

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 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Using TensorFlow backend.\n"
     ]
    }
   ],
   "source": [
    "# This demo draws heavily from the handwritten digit example in\n",
    "# Chapter 2 of Francois Chollet's \"Deep Learning with Python\" book.\n",
    "# I've added a simpler single-layer example first before moving to\n",
    "# the 2-layer example. -George Chen (CMU Fall 2017)\n",
    "\n",
    "%matplotlib inline\n",
    "import matplotlib.pyplot as plt\n",
    "import numpy as np\n",
    "\n",
    "from tensorflow.python import keras\n",
    "from keras.datasets import mnist\n",
    "from keras.models import Sequential\n",
    "from keras.layers import Dense\n",
    "\n",
    "(train_images, train_labels), (test_images, test_labels) = mnist.load_data()\n",
    "\n",
    "flattened_train_images = train_images.reshape(len(train_images), -1)  # flattens out each training image\n",
    "flattened_train_images = flattened_train_images.astype(np.float32) / 255  # rescale to be between 0 and 1\n",
    "flattened_test_images = test_images.reshape(len(test_images), -1)  # flattens out each test image\n",
    "flattened_test_images = flattened_test_images.astype(np.float32) / 255  # rescale to be between 0 and 1\n",
    "\n",
    "from keras.utils import to_categorical\n",
    "train_labels_categorical = to_categorical(train_labels)\n",
    "test_labels_categorical = to_categorical(test_labels)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "5"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "train_labels[0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0., 0., 0., 0., 0., 1., 0., 0., 0., 0.], dtype=float32)"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "train_labels_categorical[0]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Model: \"sequential_1\"\n",
      "_________________________________________________________________\n",
      "Layer (type)                 Output Shape              Param #   \n",
      "=================================================================\n",
      "dense_1 (Dense)              (None, 10)                7850      \n",
      "=================================================================\n",
      "Total params: 7,850\n",
      "Trainable params: 7,850\n",
      "Non-trainable params: 0\n",
      "_________________________________________________________________\n"
     ]
    }
   ],
   "source": [
    "# extremely shallow single-layer model\n",
    "single_layer_model = Sequential()  # this is Keras's way of specifying a model that is a single sequence of layers\n",
    "single_layer_model.add(Dense(10, activation='softmax', input_shape=(784,)))\n",
    "single_layer_model.summary()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "single_layer_model.compile(optimizer='adam',\n",
    "                           loss='categorical_crossentropy',\n",
    "                           metrics=['accuracy'])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Train on 48000 samples, validate on 12000 samples\n",
      "Epoch 1/5\n",
      "48000/48000 [==============================] - 1s 23us/step - loss: 0.7324 - accuracy: 0.8216 - val_loss: 0.4063 - val_accuracy: 0.8978\n",
      "Epoch 2/5\n",
      "48000/48000 [==============================] - 1s 24us/step - loss: 0.3882 - accuracy: 0.8972 - val_loss: 0.3352 - val_accuracy: 0.9096\n",
      "Epoch 3/5\n",
      "48000/48000 [==============================] - 1s 21us/step - loss: 0.3376 - accuracy: 0.9070 - val_loss: 0.3066 - val_accuracy: 0.9155\n",
      "Epoch 4/5\n",
      "48000/48000 [==============================] - 1s 19us/step - loss: 0.3141 - accuracy: 0.9133 - val_loss: 0.2933 - val_accuracy: 0.9186\n",
      "Epoch 5/5\n",
      "48000/48000 [==============================] - 1s 20us/step - loss: 0.2999 - accuracy: 0.9169 - val_loss: 0.2841 - val_accuracy: 0.9202\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "<keras.callbacks.callbacks.History at 0x64be81f10>"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "single_layer_model.fit(flattened_train_images,\n",
    "                       train_labels_categorical,\n",
    "                       validation_split=0.2,\n",
    "                       epochs=5,\n",
    "                       batch_size=128)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Model: \"sequential_2\"\n",
      "_________________________________________________________________\n",
      "Layer (type)                 Output Shape              Param #   \n",
      "=================================================================\n",
      "dense_2 (Dense)              (None, 512)               401920    \n",
      "_________________________________________________________________\n",
      "dense_3 (Dense)              (None, 10)                5130      \n",
      "=================================================================\n",
      "Total params: 407,050\n",
      "Trainable params: 407,050\n",
      "Non-trainable params: 0\n",
      "_________________________________________________________________\n"
     ]
    }
   ],
   "source": [
    "# two-layer model\n",
    "two_layer_model = Sequential()  # this is Keras's way of specifying a model that is a single sequence of layers\n",
    "two_layer_model.add(Dense(512, activation='relu', input_shape=(784,)))\n",
    "two_layer_model.add(Dense(10, activation='softmax'))\n",
    "two_layer_model.compile(optimizer='adam',\n",
    "                        loss='categorical_crossentropy',\n",
    "                        metrics=['accuracy'])\n",
    "two_layer_model.summary()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Train on 48000 samples, validate on 12000 samples\n",
      "Epoch 1/5\n",
      "48000/48000 [==============================] - 4s 82us/step - loss: 0.2961 - accuracy: 0.9159 - val_loss: 0.1568 - val_accuracy: 0.9561\n",
      "Epoch 2/5\n",
      "48000/48000 [==============================] - 3s 73us/step - loss: 0.1219 - accuracy: 0.9647 - val_loss: 0.1098 - val_accuracy: 0.9673\n",
      "Epoch 3/5\n",
      "48000/48000 [==============================] - 4s 75us/step - loss: 0.0780 - accuracy: 0.9779 - val_loss: 0.0939 - val_accuracy: 0.9716\n",
      "Epoch 4/5\n",
      "48000/48000 [==============================] - 4s 74us/step - loss: 0.0560 - accuracy: 0.9834 - val_loss: 0.0871 - val_accuracy: 0.9756\n",
      "Epoch 5/5\n",
      "48000/48000 [==============================] - 4s 75us/step - loss: 0.0408 - accuracy: 0.9884 - val_loss: 0.0856 - val_accuracy: 0.9758\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "<keras.callbacks.callbacks.History at 0x64c90bb10>"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "two_layer_model.fit(flattened_train_images,\n",
    "                    train_labels_categorical,\n",
    "                    validation_split=0.2,\n",
    "                    epochs=5,\n",
    "                    batch_size=128)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Finally evaluate on test data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10000/10000 [==============================] - 0s 25us/step\n",
      "Test accuracy: 0.9214000105857849\n"
     ]
    }
   ],
   "source": [
    "test_loss, test_acc = single_layer_model.evaluate(flattened_test_images, test_labels_categorical)\n",
    "print('Test accuracy:', test_acc)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "10000/10000 [==============================] - 0s 46us/step\n",
      "Test accuracy: 0.9764999747276306\n"
     ]
    }
   ],
   "source": [
    "test_loss, test_acc = two_layer_model.evaluate(flattened_test_images, test_labels_categorical)\n",
    "print('Test accuracy:', test_acc)"
   ]
  }
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