Numpy recarray.ptp() function | Python
Last Updated :
27 Sep, 2019
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In numpy, arrays may have a data-types containing fields, analogous to columns in a spreadsheet. An example is
Python3
[(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)
# Python program explaining# numpy.recarray.ptp() method # importing numpy as geekimport 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 1out_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 0out_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 valueout_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 1out_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 0out_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 valueout_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
