[Tensorflow] 什麼是 Placeholder ？

之前有點不太清楚 Placeholder 到底在做什麼

下面是我查到的結果，詳細的可以

A placeholder is simply a variable that we will assign data to at a later date --- Placeholders - Learning Tensorflow.com

簡單來講就是一個之後可以儲存值的變數 （想像一下 向量 或是 Tensor ）

x = tf.placeholder("float", 3)

First, we import tensorflow as normal. Then we create a placeholder called x, i.e. a place in memory where we will store value later on. The 3 on this line denotes that we will store three values in this placeholder.

所以，等等 x 可以被儲存3個浮點數進去

當然，也可以不指定 x 的儲存數量，例如以下

x = tf.placeholder("float", None)