python - Keras 后端函数中的参数 keepdims 是做什么用的？

Question

Keras 后端有很多函数都带有 keepdims 参数。比如

sum(x, axis=None, keepdims=False)

我找不到任何关于这意味着什么的解释。有人可以解释它的作用吗？

此外，axis 为None 是什么意思？这和说 axis = -1 一样吗？

Answer 1

这些不是 keras 特定参数，而是 numpy.sum 参数。

axis : None or int or tuple of ints, optional

Axis or axes along which a sum is performed. The default (axis = None) is perform a sum over all the dimensions of the input array. axis may be negative, in which case it counts from the last to the first axis.

New in version 1.7.0.

If this is a tuple of ints, a sum is performed on multiple axes, instead of a single axis or all the axes as before.

keepdims : bool, optional

If this is set to True, the axes which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the original arr.

here is the source