Numpy recarray.tolist() function | Python
Last Updated :
27 Sep, 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.tolist()
function is used to make the array as a (possibly nested) list.It return a copy of the array data as a (nested) Python list. Data items are converted to the nearest compatible Python type.
Syntax : numpy.recarray.tolist()
Parameters:
None
Return : [list] The possibly nested list of array elements.
Code #1 :
Python3
# Python program explaining
# numpy.recarray.tolist() 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.tolist methods
# to float record array
out_arr = rec_arr.a.tolist()
print ("Output list of float record array ", out_arr)
# applying recarray.tolist methods
# to int record array
out_arr = rec_arr.b.tolist()
print ("Output list of int record array ", 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 list of float record array [[5.0, 3.0, 6.0], [9.0, 5.0, -12.0]]
Output list of int record array [[2, -4, 9], [1, 4, -7]]
Code #2 :
We are applying
numpy.recarray.tolist()
to whole record array.
Python3
# Python program explaining
# numpy.recarray.tolist() 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, -7)],
[(9.0, 1), (6.0, 4), (-2.0, -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)
# applying recarray.tolist methods to
# record array in default order
out_arr = rec_arr.tolist()
print ("Output list of record array ", out_arr)
Output:
Input array : [[( 5., 2) ( 3., 4) ( 6., -7)]
[( 9., 1) ( 6., 4) (-2., -7)]]
Output list of record array [[(5.0, 2), (3.0, 4), (6.0, -7)], [(9.0, 1), (6.0, 4), (-2.0, -7)]]
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