Numpy recarray.ptp() function | Python

In numpy, arrays may have a data-types containing fields, analogous to columns in a spreadsheet. An example is [(a, int), (b, float)], where each entry in the array is a pair of (int, float). Normally, these attributes are accessed using dictionary lookups such as arr['a'] and arr['b']. Record arrays allow the fields to be accessed as members of the array, using arr.a and arr.b.

numpy.recarray.ptp() function returns Peak to peak (maximum – minimum) value along a given axis.

Syntax : numpy.recarray.ptp(axis=None, out=None)

Parameters:

axis : [int, optional] Axis along which to find the peaks. By default, flatten the array.
out : [ndarray, optional] A location into which the result is stored.
  -> If provided, it must have a shape that the inputs broadcast to.
  -> If not provided or None, a freshly-allocated array is returned.

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

Code #1 :

# Python program explaining
# numpy.recarray.ptp() method

# importing numpy as geek
import numpy as geek

# creating input array with 2 different field
in_arr = geek.array([[(5.0, 2), (3.0, -4), (6.0, 9)],
                     [(9.0, 1), (5.0, 4), (-12.0, -7)]],
                     dtype =[('a', float), ('b', int)])

print ("Input array : ", in_arr)

# convert it to a record array,
# using arr.view(np.recarray)
rec_arr = in_arr.view(geek.recarray)
print("Record array of float: ", rec_arr.a)
print("Record array of int: ", rec_arr.b)

# applying recarray.ptp methods
# to float record array along axis 1
out_arr = rec_arr.a.ptp( axis = 1)
print ("Output range array of float along axis 1: ", out_arr)

# applying recarray.ptp methods
# to float record array along axis 0
out_arr = rec_arr.a.ptp( axis = 0)
print ("Output range array of float along axis 0: ", out_arr)

# applying recarray.ptp methods
# to float record array along -1 axis
out_arr = rec_arr.a.ptp( axis = -1)
print ("Output range array of float along -1 axis : ", out_arr)

# applying recarray.ptp methods
# to int record array along default axis value
out_arr = rec_arr.a.ptp()
print ("Output range of float array elements array along default axis: ", out_arr)


# applying recarray.ptp methods
# to int record array along axis 1
out_arr = rec_arr.b.ptp( axis = 1)
print ("Output range array of int along axis 1: ", out_arr)

# applying recarray.ptp methods
# to int record array along axis 0
out_arr = rec_arr.b.ptp( axis = 0)
print ("Output range array of int along axis 0: ", out_arr)

# applying recarray.ptp methods
# to int record array along -1 axis
out_arr = rec_arr.b.ptp( axis = -1)
print ("Output range array of int along -1 axis : ", out_arr)


# applying recarray.ptp methods
# to int record array along default axis value
out_arr = rec_arr.b.ptp()
print ("Output range of int array elements array along default axis: ", out_arr)

Output:

Input array :  [[(  5.,  2) (  3., -4) (  6.,  9)]
 [(  9.,  1) (  5.,  4) (-12., -7)]]
Record array of float:  [[  5.   3.   6.]
 [  9.   5. -12.]]
Record array of int:  [[ 2 -4  9]
 [ 1  4 -7]]
Output range array of float along axis 1:  [ 3. 21.]
Output range array of float along axis 0:  [ 4.  2. 18.]
Output range array of float along -1 axis :  [ 3. 21.]
Output range of float array elements array along default axis:  21.0
Output range array of int along axis 1:  [13 11]
Output range array of int along axis 0:  [ 1  8 16]
Output range array of int along -1 axis :  [13 11]
Output range of int array elements array along default axis:  16