`numpy.ma.core:ptp`

source: /numpy/ma/core.py :7018

Signature

   def     ptp (    obj    ,    axis    =  None   ,    out    =  None   ,    fill_value    =  None   ,    keepdims    =  <no value>     )

Summary

Return (maximum - minimum) along the given dimension (i.e. peak-to-peak value).

Extended Summary

Parameters

axis : {None, int}, optional: Axis along which to find the peaks. If None (default) the flattened array is used.
out : {None, array_like}, optional: 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 will be cast if necessary.
fill_value : scalar or None, optional: Value used to fill in the masked values.
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 array.

Returns

ptp : ndarray.: A new array holding the result, unless out was specified, in which case a reference to out is returned.

Examples

import numpy as np
x = np.ma.MaskedArray([[4, 9, 2, 10],
                       [6, 9, 7, 12]])

x.ptp(axis=1)

x.ptp(axis=0)

x.ptp()

This example shows that a negative value can be returned when the input is an array of signed integers.

y = np.ma.MaskedArray([[1, 127],
                       [0, 127],
                       [-1, 127],
                       [-2, 127]], dtype=np.int8)
y.ptp(axis=1)

A work-around is to use the `view()` method to view the result as unsigned integers with the same bit width:

y.ptp(axis=1).view(np.uint8)

Aliases

numpy.ma.ptp