https://www.tensorflow.org/versions/r0.12/api_docs/python/math_ops.html#reduce_mean
tf.reduce_mean(input_tensor, axis=None, keep_dims=False, name=None, reduction_indices=None)
計算tensor中各個維度上元素的平均值. 在給定維度axis上進行刪減. keep_dims被設置為false的話, 原始變量的維度會減少1. 如果不對axis進行賦值, 那么返回所有元素的平均值.
例子:
# 'x' is [[1., 1.] # [2., 2.]] tf.reduce_mean(x) ==> 1.5 tf.reduce_mean(x, 0) ==> [1.5, 1.5] tf.reduce_mean(x, 1) ==> [1., 2.]