Starting With Tensorflow.ipynb

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  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import tensorflow as tf"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Tensors - units of data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "node1 = tf.constant(3.0, tf.float32) # a constant node"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Tensor(\"Const:0\", shape=(), dtype=float32)\n"
     ]
    }
   ],
   "source": [
    "print node1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "node2 = tf.constant(5.0, tf.float32)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "output = tf.add(node1, node2) # a simple operation on two nodes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Tensor(\"Add:0\", shape=(), dtype=float32)\n"
     ]
    }
   ],
   "source": [
    "print output # returns a tensor whose value can be seen when graph runs"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<dtype: 'float32'>\n"
     ]
    }
   ],
   "source": [
    "print output.dtype"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "() <tensorflow.python.framework.ops.Graph object at 0x7fbe62c07d50>\n"
     ]
    }
   ],
   "source": [
    "print output._shape, output.graph"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "node3 = tf.Variable(1, name=\"node3\", dtype=\"float32\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Tensor(\"node3/read:0\", shape=(), dtype=float32)\n"
     ]
    }
   ],
   "source": [
    "print node3 # a variable node whose value changes during TF computation and maintains states with variables"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "node5 = tf.placeholder(\"float32\", name=\"node5\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# graphs - units of computations"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "defGraph = tf.get_default_graph()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<tensorflow.python.framework.ops.Graph object at 0x7fbe62c07d50>\n"
     ]
    }
   ],
   "source": [
    "print defGraph"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "assert node3.graph is defGraph"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# graph and its context\n",
    "contextGraph = tf.Graph()\n",
    "with contextGraph.as_default():\n",
    "    node4 = tf.constant(30.0)\n",
    "    assert node4.graph is contextGraph\n",
    "    #assert node4.graph is defGraph\n",
    "    assert node3.graph is defGraph\n",
    "\n",
    "assert node4.graph is contextGraph\n",
    "assert node3.graph is defGraph\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# using device with graphs\n",
    "#with defGraph.device('/gpu:0'):\n",
    "#   node5 = tf.constant(12)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "with defGraph.device('/cpu:0'):\n",
    "    node6 = tf.constant(12.9)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# name scopes\n",
    "with defGraph.name_scope(\"nested\") as scope:\n",
    "    pass\n",
    "    #nested_c = tf.constant(10.0, name=\"c\")\n",
    "    #print nested_c.name\n",
    "    #assert nested_c.name == \"nested/c:0\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[<tf.Operation 'Const' type=Const>,\n",
       " <tf.Operation 'Const_1' type=Const>,\n",
       " <tf.Operation 'Add' type=Add>,\n",
       " <tf.Operation 'node3/initial_value' type=Const>,\n",
       " <tf.Operation 'node3' type=VariableV2>,\n",
       " <tf.Operation 'node3/Assign' type=Assign>,\n",
       " <tf.Operation 'node3/read' type=Identity>,\n",
       " <tf.Operation 'node5' type=Placeholder>,\n",
       " <tf.Operation 'Const_2' type=Const>]"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "tf.Graph.get_operations(defGraph) # to list the operations on graph"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[<tf.Operation 'Const' type=Const>]"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "tf.Graph.get_operations(contextGraph)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "8.0\n",
      "8.0\n",
      "3.0\n",
      "10.8999996185\n"
     ]
    }
   ],
   "source": [
    "# sessions -  to execute the entire graph\n",
    "with tf.Session() as sess:\n",
    "    sess.run(tf.global_variables_initializer())\n",
    "    print sess.run(output) # like this\n",
    "    print output.eval() # or like this\n",
    "    print node1.eval()\n",
    "    # feeding the placeholder like this\n",
    "    node5 = sess.run(node5, feed_dict={node5:10.9})\n",
    "    print node5"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[<tensorflow.python.ops.variables.Variable object at 0x7fbe62c075d0>]\n"
     ]
    }
   ],
   "source": [
    "print tf.global_variables()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[<tensorflow.python.ops.variables.Variable object at 0x7fbe62c075d0>]\n"
     ]
    }
   ],
   "source": [
    "print tf.trainable_variables()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
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