机器学习系列-tensorflow-02-基本操作运算

tensorflow常数操作

```
import tensorflow as tf
# 定义两个常数，a和b
a = tf.constant(2)
b = tf.constant(3)
# 执行默认图运算
with tf.Session() as sess:
print("a=2, b=3")
print("Addition with constants: %i" % sess.run(a+b))
print("Multiplication with constants: %i" % sess.run(a*b))
```
**结果**
a=2, b=3
Addition with constants: 5
Multiplication with constants: 6

---

tensorflow变量操作

变量作为图形输入，构造器的返回值作为变量的输出，在运行会话时，传入变量的值，在进行运算。
```
import tensorflow as tf
# 定义两个变量
a = tf.placeholder(tf.int16)
b = tf.placeholder(tf.int16)

定义加法和乘法运算

add = tf.add(a, b)

mul = tf.multiply(a, b)

启动默认图进行运算

with tf.Session() as sess:

# 传入变量值，进行运算

print("Addition with variables: %i" % sess.run(add, feed_dict={a: 2, b: 3}))

print("Multiplication with variables: %i" % sess.run(mul, feed_dict={a: 2, b: 3}))

**结果**
Addition with variables: 5
Multiplication with variables: 6

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<h1 style="background-color:#FF69B4; font-family:verdana; font-size:25px; text-align:center; font-weight:bold; color:white; ">tensorflow矩阵常量操作</h1>

import tensorflow as tf

创建一个1X2的常数矩阵

matrix1 = tf.constant([[3., 3.]])

创建一个2X1的常数矩阵

matrix2 = tf.constant([[2.],[2.]])

定义矩阵乘法运算multiplication

product = tf.matmul(matrix1, matrix2)

启动默认图进行运算

with tf.Session() as sess:

result = sess.run(product)

print(result)

**结果**
[[12.]]

<h1 style="background-color:#FF69B4; font-family:verdana; font-size:25px; text-align:center; font-weight:bold; color:white; ">简单例子</h1>

import tensorflow as tf

hello = tf.constant('Hello, TensorFlow!')

sess = tf.Session()

print(sess.run(hello))

**结果**
b'Hello, TensorFlow!'

-------------------------------------
参考：
Author: Aymeric Damien
Project: https://github.com/aymericdamien/TensorFlow-Examples/