Python Numpy recarray.tolist()函数

在numpy中，数组可以有一个包含字段的数据类型，类似于电子表格中的列。一个例子是[(a, int), (b, float)] ，其中数组中的每个条目是一对(int, float)。通常情况下，这些属性使用字典查询，如arr[‘a’] 和arr[‘b’] 。

numpy.recarray.tolist()函数被用来将数组作为一个（可能是嵌套的）列表，它返回一个作为（嵌套的）Python列表的数组数据副本。数据项被转换为最接近的兼容Python类型。

语法: numpy.recarray.tolist()

参数:
None

返回： [list] 可能嵌套的数组元素列表。

代码#1：

# 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)

输出:

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]]

代码#2：

我们正在对整个记录数组应用numpy.recarray.tolist()。

# 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)

输出:

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)]]