1_tensorflow基础.ipynb

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   "source": [
    "import tensorflow as tf"
   ]
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     "text": [
      "b'hello'\n"
     ]
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    "constant_1 = tf.constant('hello')\n",
    "with tf.Session() as sess:\n",
    "    output = sess.run(constant_1)\n",
    "    print(output)"
   ]
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   "outputs": [
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     "name": "stdout",
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     "text": [
      "b'world'\n"
     ]
    }
   ],
   "source": [
    "constant_2 = tf.constant('world')\n",
    "with tf.Session() as sess:\n",
    "    with tf.device('/cpu:0'):\n",
    "        output = sess.run(constant_2)\n",
    "        print(output)"
   ]
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     "text": [
      "[-2 -2]\n"
     ]
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   "source": [
    "# 交互式\n",
    "x = tf.Variable([1,2])\n",
    "y = tf.Variable([3,4])\n",
    "init = tf.global_variables_initializer()\n",
    "with tf.Session() as sess:\n",
    "    sess.run(init)   \n",
    "#     sub = tf.multiply(x,y)\n",
    "    sub = tf.subtract(x,y)\n",
    "    print(sub.eval())"
   ]
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     "text": [
      "2\n"
     ]
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   "source": [
    "# 占位符和feed_dict\n",
    "input_placeholder = tf.placeholder(tf.int32)\n",
    "with tf.Session() as sess:\n",
    "    print(sess.run(input_placeholder,feed_dict={input_placeholder:2}))"
   ]
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      "[[-0.13862522 -0.24789245]\n",
      " [-0.22179745  0.9156514 ]]\n"
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   "source": [
    "# 自定义的计算图\n",
    "tf.reset_default_graph()\n",
    "g = tf.Graph()\n",
    "with g.as_default():\n",
    "    tf.set_random_seed(1234)\n",
    "    x = tf.random_normal([2,2])\n",
    "    init_op = tf.global_variables_initializer()\n",
    "with tf.Session(graph=g) as sess:\n",
    "    xvalue,_ = sess.run([x,init_op]) # init_op没有返回tensor\n",
    "    print(xvalue)"
   ]
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