将tensor转array

如果对tensor使用extend方法，如下面这个例子：

import tensorflow as tf

a = tf.convert_to_tensor([1,2,3])
b = []
with tf.Session() as sess:
    b.extend(a)

会报错“Tensor objects are only iterable when eager execution is enabled. To iterate over this tensor use tf.map_fn.”

需要把tensor转换为数组，通过tensor.eval()方法来转换,如下面例子：

a = tf.convert_to_tensor([1,2,3])
b = []
with tf.Session() as sess:
    c = a.eval()
    b.extend(c)
    print(type(c))  # <class 'numpy.ndarray'>

注意：这一句要放到sess里面

c = a.eval()