ch02-基本概念/03-操作.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "import tensorflow as tf"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 定义常量"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 定义常量\n",
    "a = tf.constant(2)\n",
    "b = tf.constant(3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "a: 2\n",
      "b: 3\n",
      "Addition with constants: 5\n",
      "Multiplication with constants: 6\n"
     ]
    }
   ],
   "source": [
    "# 创建会话, 并执行计算操作\n",
    "with tf.Session() as sess:\n",
    "    print(\"a: %i\" % sess.run(a))\n",
    "    print(\"b: %i\" % sess.run(b))\n",
    "    print(\"Addition with constants: %i\" % sess.run(a + b))\n",
    "    print(\"Multiplication with constants: %i\" % sess.run(a * b))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 占位符操作"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 占位符操作\n",
    "# x = tf.placeholder(dtype, shape, name)\n",
    "x = tf.placeholder(tf.int16, shape=(), name='x')\n",
    "y = tf.placeholder(tf.int16, shape=(), name='y')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 仅仅定义 操作本身\n",
    "# 具体什么值，在运行时输入就好了\n",
    "add = tf.add(x, y)\n",
    "mul = tf.multiply(x, y)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Addition with variables: 15\n",
      "Multiplication with variables: 6\n"
     ]
    }
   ],
   "source": [
    "# 加载默认 数据流图\n",
    "# 神经网络中，X、y高维数据\n",
    "with tf.Session() as sess:\n",
    "    print(\"Addition with variables: %i\" % sess.run(add, feed_dict={x: 10, y: 5}))\n",
    "    print(\"Multiplication with variables: %i\" % sess.run(mul, feed_dict={x: 2, y: 3}))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "ename": "InvalidArgumentError",
     "evalue": "You must feed a value for placeholder tensor 'y' with dtype int16\n\t [[node y (defined at <ipython-input-5-6549847aedc1>:4)  = Placeholder[dtype=DT_INT16, shape=[], _device=\"/job:localhost/replica:0/task:0/device:CPU:0\"]()]]\n\nCaused by op 'y', defined at:\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/runpy.py\", line 193, in _run_module_as_main\n    \"__main__\", mod_spec)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/runpy.py\", line 85, in _run_code\n    exec(code, run_globals)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel_launcher.py\", line 16, in <module>\n    app.launch_new_instance()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/traitlets/config/application.py\", line 658, in launch_instance\n    app.start()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelapp.py\", line 478, in start\n    self.io_loop.start()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/ioloop.py\", line 177, in start\n    super(ZMQIOLoop, self).start()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tornado/ioloop.py\", line 888, in start\n    handler_func(fd_obj, events)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tornado/stack_context.py\", line 277, in null_wrapper\n    return fn(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/zmqstream.py\", line 440, in _handle_events\n    self._handle_recv()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/zmqstream.py\", line 472, in _handle_recv\n    self._run_callback(callback, msg)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/zmqstream.py\", line 414, in _run_callback\n    callback(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tornado/stack_context.py\", line 277, in null_wrapper\n    return fn(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelbase.py\", line 281, in dispatcher\n    return self.dispatch_shell(stream, msg)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelbase.py\", line 232, in dispatch_shell\n    handler(stream, idents, msg)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelbase.py\", line 397, in execute_request\n    user_expressions, allow_stdin)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/ipkernel.py\", line 208, in do_execute\n    res = shell.run_cell(code, store_history=store_history, silent=silent)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/zmqshell.py\", line 533, in run_cell\n    return super(ZMQInteractiveShell, self).run_cell(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/IPython/core/interactiveshell.py\", line 2728, in run_cell\n    interactivity=interactivity, compiler=compiler, result=result)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/IPython/core/interactiveshell.py\", line 2850, in run_ast_nodes\n    if self.run_code(code, result):\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/IPython/core/interactiveshell.py\", line 2910, in run_code\n    exec(code_obj, self.user_global_ns, self.user_ns)\n  File \"<ipython-input-5-6549847aedc1>\", line 4, in <module>\n    y = tf.placeholder(tf.int16, shape=(), name='y')\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/ops/array_ops.py\", line 1747, in placeholder\n    return gen_array_ops.placeholder(dtype=dtype, shape=shape, name=name)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/ops/gen_array_ops.py\", line 5206, in placeholder\n    \"Placeholder\", dtype=dtype, shape=shape, name=name)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/framework/op_def_library.py\", line 787, in _apply_op_helper\n    op_def=op_def)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/util/deprecation.py\", line 488, in new_func\n    return func(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/framework/ops.py\", line 3274, in create_op\n    op_def=op_def)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/framework/ops.py\", line 1770, in __init__\n    self._traceback = tf_stack.extract_stack()\n\nInvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'y' with dtype int16\n\t [[node y (defined at <ipython-input-5-6549847aedc1>:4)  = Placeholder[dtype=DT_INT16, shape=[], _device=\"/job:localhost/replica:0/task:0/device:CPU:0\"]()]]\n",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mInvalidArgumentError\u001b[0m                      Traceback (most recent call last)",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36m_do_call\u001b[0;34m(self, fn, *args)\u001b[0m\n\u001b[1;32m   1333\u001b[0m     \u001b[0;32mtry\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m-> 1334\u001b[0;31m       \u001b[0;32mreturn\u001b[0m \u001b[0mfn\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m   1335\u001b[0m     \u001b[0;32mexcept\u001b[0m \u001b[0merrors\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mOpError\u001b[0m \u001b[0;32mas\u001b[0m \u001b[0me\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36m_run_fn\u001b[0;34m(feed_dict, fetch_list, target_list, options, run_metadata)\u001b[0m\n\u001b[1;32m   1318\u001b[0m       return self._call_tf_sessionrun(\n\u001b[0;32m-> 1319\u001b[0;31m           options, feed_dict, fetch_list, target_list, run_metadata)\n\u001b[0m\u001b[1;32m   1320\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36m_call_tf_sessionrun\u001b[0;34m(self, options, feed_dict, fetch_list, target_list, run_metadata)\u001b[0m\n\u001b[1;32m   1406\u001b[0m         \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_session\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0moptions\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mfeed_dict\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mfetch_list\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mtarget_list\u001b[0m\u001b[0;34m,\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m-> 1407\u001b[0;31m         run_metadata)\n\u001b[0m\u001b[1;32m   1408\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mInvalidArgumentError\u001b[0m: You must feed a value for placeholder tensor 'y' with dtype int16\n\t [[{{node y}} = Placeholder[dtype=DT_INT16, shape=[], _device=\"/job:localhost/replica:0/task:0/device:CPU:0\"]()]]",
      "\nDuring handling of the above exception, another exception occurred:\n",
      "\u001b[0;31mInvalidArgumentError\u001b[0m                      Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-8-a5baaf0a4e30>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0;32mwith\u001b[0m \u001b[0mtf\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mSession\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m)\u001b[0m \u001b[0;32mas\u001b[0m \u001b[0msess\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      3\u001b[0m     \u001b[0;31m# 不填充数据，直接执行操作，报错\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 4\u001b[0;31m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m\"Addition with variables: %i\"\u001b[0m \u001b[0;34m%\u001b[0m \u001b[0msess\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mrun\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0madd\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m      5\u001b[0m     \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m\"Multiplication with variables: %i\"\u001b[0m \u001b[0;34m%\u001b[0m \u001b[0msess\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mrun\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mmul\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36mrun\u001b[0;34m(self, fetches, feed_dict, options, run_metadata)\u001b[0m\n\u001b[1;32m    927\u001b[0m     \u001b[0;32mtry\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    928\u001b[0m       result = self._run(None, fetches, feed_dict, options_ptr,\n\u001b[0;32m--> 929\u001b[0;31m                          run_metadata_ptr)\n\u001b[0m\u001b[1;32m    930\u001b[0m       \u001b[0;32mif\u001b[0m \u001b[0mrun_metadata\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m    931\u001b[0m         \u001b[0mproto_data\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mtf_session\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mTF_GetBuffer\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mrun_metadata_ptr\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36m_run\u001b[0;34m(self, handle, fetches, feed_dict, options, run_metadata)\u001b[0m\n\u001b[1;32m   1150\u001b[0m     \u001b[0;32mif\u001b[0m \u001b[0mfinal_fetches\u001b[0m \u001b[0;32mor\u001b[0m \u001b[0mfinal_targets\u001b[0m \u001b[0;32mor\u001b[0m \u001b[0;34m(\u001b[0m\u001b[0mhandle\u001b[0m \u001b[0;32mand\u001b[0m \u001b[0mfeed_dict_tensor\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m   1151\u001b[0m       results = self._do_run(handle, final_targets, final_fetches,\n\u001b[0;32m-> 1152\u001b[0;31m                              feed_dict_tensor, options, run_metadata)\n\u001b[0m\u001b[1;32m   1153\u001b[0m     \u001b[0;32melse\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m   1154\u001b[0m       \u001b[0mresults\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0;34m[\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36m_do_run\u001b[0;34m(self, handle, target_list, fetch_list, feed_dict, options, run_metadata)\u001b[0m\n\u001b[1;32m   1326\u001b[0m     \u001b[0;32mif\u001b[0m \u001b[0mhandle\u001b[0m \u001b[0;32mis\u001b[0m \u001b[0;32mNone\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m   1327\u001b[0m       return self._do_call(_run_fn, feeds, fetches, targets, options,\n\u001b[0;32m-> 1328\u001b[0;31m                            run_metadata)\n\u001b[0m\u001b[1;32m   1329\u001b[0m     \u001b[0;32melse\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m   1330\u001b[0m       \u001b[0;32mreturn\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_do_call\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0m_prun_fn\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mhandle\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mfeeds\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mfetches\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;32m~/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/client/session.py\u001b[0m in \u001b[0;36m_do_call\u001b[0;34m(self, fn, *args)\u001b[0m\n\u001b[1;32m   1346\u001b[0m           \u001b[0;32mpass\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m   1347\u001b[0m       \u001b[0mmessage\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0merror_interpolation\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0minterpolate\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mmessage\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0m_graph\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m-> 1348\u001b[0;31m       \u001b[0;32mraise\u001b[0m \u001b[0mtype\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0me\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mnode_def\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mop\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mmessage\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m   1349\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m   1350\u001b[0m   \u001b[0;32mdef\u001b[0m \u001b[0m_extend_graph\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
      "\u001b[0;31mInvalidArgumentError\u001b[0m: You must feed a value for placeholder tensor 'y' with dtype int16\n\t [[node y (defined at <ipython-input-5-6549847aedc1>:4)  = Placeholder[dtype=DT_INT16, shape=[], _device=\"/job:localhost/replica:0/task:0/device:CPU:0\"]()]]\n\nCaused by op 'y', defined at:\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/runpy.py\", line 193, in _run_module_as_main\n    \"__main__\", mod_spec)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/runpy.py\", line 85, in _run_code\n    exec(code, run_globals)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel_launcher.py\", line 16, in <module>\n    app.launch_new_instance()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/traitlets/config/application.py\", line 658, in launch_instance\n    app.start()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelapp.py\", line 478, in start\n    self.io_loop.start()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/ioloop.py\", line 177, in start\n    super(ZMQIOLoop, self).start()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tornado/ioloop.py\", line 888, in start\n    handler_func(fd_obj, events)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tornado/stack_context.py\", line 277, in null_wrapper\n    return fn(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/zmqstream.py\", line 440, in _handle_events\n    self._handle_recv()\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/zmqstream.py\", line 472, in _handle_recv\n    self._run_callback(callback, msg)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/zmq/eventloop/zmqstream.py\", line 414, in _run_callback\n    callback(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tornado/stack_context.py\", line 277, in null_wrapper\n    return fn(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelbase.py\", line 281, in dispatcher\n    return self.dispatch_shell(stream, msg)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelbase.py\", line 232, in dispatch_shell\n    handler(stream, idents, msg)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/kernelbase.py\", line 397, in execute_request\n    user_expressions, allow_stdin)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/ipkernel.py\", line 208, in do_execute\n    res = shell.run_cell(code, store_history=store_history, silent=silent)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/ipykernel/zmqshell.py\", line 533, in run_cell\n    return super(ZMQInteractiveShell, self).run_cell(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/IPython/core/interactiveshell.py\", line 2728, in run_cell\n    interactivity=interactivity, compiler=compiler, result=result)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/IPython/core/interactiveshell.py\", line 2850, in run_ast_nodes\n    if self.run_code(code, result):\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/IPython/core/interactiveshell.py\", line 2910, in run_code\n    exec(code_obj, self.user_global_ns, self.user_ns)\n  File \"<ipython-input-5-6549847aedc1>\", line 4, in <module>\n    y = tf.placeholder(tf.int16, shape=(), name='y')\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/ops/array_ops.py\", line 1747, in placeholder\n    return gen_array_ops.placeholder(dtype=dtype, shape=shape, name=name)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/ops/gen_array_ops.py\", line 5206, in placeholder\n    \"Placeholder\", dtype=dtype, shape=shape, name=name)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/framework/op_def_library.py\", line 787, in _apply_op_helper\n    op_def=op_def)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/util/deprecation.py\", line 488, in new_func\n    return func(*args, **kwargs)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/framework/ops.py\", line 3274, in create_op\n    op_def=op_def)\n  File \"/Users/mgbook/.pyenv/versions/3.6.4rc1/lib/python3.6/site-packages/tensorflow/python/framework/ops.py\", line 1770, in __init__\n    self._traceback = tf_stack.extract_stack()\n\nInvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'y' with dtype int16\n\t [[node y (defined at <ipython-input-5-6549847aedc1>:4)  = Placeholder[dtype=DT_INT16, shape=[], _device=\"/job:localhost/replica:0/task:0/device:CPU:0\"]()]]\n"
     ]
    }
   ],
   "source": [
    "# 加载默认 数据流图\n",
    "with tf.Session() as sess:\n",
    "    # 不填充数据，直接执行操作，报错\n",
    "    print(\"Addition with variables: %i\" % sess.run(add))\n",
    "    print(\"Multiplication with variables: %i\" % sess.run(mul))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "You must feed a value for placeholder tensor 'x_1' with dtype int16\n",
    "\n",
    "你必须，给`占位符`填充数据"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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