numpy.ptp

numpy.ptp(a, axis=None, out=None, keepdims=<no value>)
[source]

Range of values (maximum  minimum) along an axis.
The name of the function comes from the acronym for ‘peak to peak’.
Parameters: 

a : array_like 
Input values. 
axis : None or int or tuple of ints, optional 
Axis along which to find the peaks. By default, flatten the array. axis may be negative, in which case it counts from the last to the first axis. If this is a tuple of ints, a reduction is performed on multiple axes, instead of a single axis or all the axes as before. 
out : array_like 
Alternative output array in which to place the result. It must have the same shape and buffer length as the expected output, but the type of the output values will be cast if necessary. 
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 input array. If the default value is passed, then keepdims will not be passed through to the ptp method of subclasses of ndarray , however any nondefault value will be. If the subclass’ method does not implement keepdims any exceptions will be raised. 
Returns: 

ptp : ndarray 
A new array holding the result, unless out was specified, in which case a reference to out is returned. 
Examples
>>> x = np.arange(4).reshape((2,2))
>>> x
array([[0, 1],
[2, 3]])
>>> np.ptp(x, axis=0)
array([2, 2])
>>> np.ptp(x, axis=1)
array([1, 1])