np.amax和np.max是同一个函数.

amax(a, axis=None, out=None, keepdims=<no value>, initial=<no value>, where=<no value>)
Return the maximum of an array or maximum along an axis.

Examples

--------
>>> a = np.arange(4).reshape((2,2))
>>> a
array([[0, 1],
	   [2, 3]])
		  
>>> np.amax(a)                   # Maximum of the flattened array
3

>>> np.amax(a, axis=None)        # Maximum of the flattened array
3

>>> np.amax(a, axis=0)           # Maxima along the first axis
array([2, 3])

>>> np.amax(a, axis=1)  		 # Maxima along the second axis
array([1, 3])

即axis不声明时,默认为 None, 这时表示取展平数组的最大值

若axis = 0, 取沿第一轴的最大值(即按行取)

若axis = 1, 取沿第二轴的最大值(即按列取)