Numpy recarray.cumprod() function | Python

Last Updated : 03 Oct, 2019

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.cumprod() function returns the cumulative product of array elements over a given axis.

Syntax : numpy.recarray.cumprod(axis=None, dtype=None, out=None) Parameters: axis : Axis along which the cumulative product is computed. The default is to compute the product of the flattened array. dtype : Type of the returned array, as well as of the accumulator in which the elements are multiplied. 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 : A new array holding the result is returned unless out is specified, in which case it is returned.

Code #1 :

Python3

# Python program explaining
# numpy.recarray.cumprod() 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.cumprod methods
# to float record array along axis 1
out_arr = rec_arr.a.cumprod( axis = 1)
print ("Output array along axis 1: ", out_arr) 

# applying recarray.cumprod methods 
# to int record array along axis 0
out_arr = rec_arr.b.cumprod(axis = 0)
print ("Output  array along axis 0: ", 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 array along axis 1:  [[   5.   15.   90.]
 [   9.   45. -540.]]
Output  array along axis 0:  [[  2  -4   9]
 [  2 -16 -63]]