機器學習系列-tensorflow-02-基本操作運算

既生喻何生亮發表於2018-10-30
機器學習

tensorflow常數操作

import tensorflow as tf
# 定義兩個常數，a和b
a = tf.constant(2)
b = tf.constant(3)
# 執行預設圖運算
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))

結果
a=2, b=3
Addition with constants: 5
Multiplication with constants: 6

tensorflow變數操作

變數作為圖形輸入，構造器的返回值作為變數的輸出，在執行會話時，傳入變數的值，在進行運算。

import tensorflow as tf
# 定義兩個變數
a = tf.placeholder(tf.int16)
b = tf.placeholder(tf.int16)

# 定義加法和乘法運算
add = tf.add(a, b)
mul = tf.multiply(a, b)

# 啟動預設圖進行運算
with tf.Session() as sess:
    # 傳入變數值，進行運算
    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}))

結果
Addition with variables: 5
Multiplication with variables: 6

tensorflow矩陣常量操作

import tensorflow as tf
# 建立一個1X2的常數矩陣
matrix1 = tf.constant([[3., 3.]])
# 建立一個2X1的常數矩陣
matrix2 = tf.constant([[2.],[2.]])
# 定義矩陣乘法運算multiplication
product = tf.matmul(matrix1, matrix2)
# 啟動預設圖進行運算
with tf.Session() as sess:
    result = sess.run(product)
    print(result)

結果
[[12.]]

簡單例子

import tensorflow as tf
hello = tf.constant(`Hello, TensorFlow!`)
sess = tf.Session()
print(sess.run(hello))

結果
b`Hello, TensorFlow!`

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

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