numpy recarray.ravel()函数| Python

在 numpy 中，数组可能具有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都是一对 (int, float)。通常，使用诸如arr['a'] and arr['b']类的字典查找来访问这些属性。记录数组允许使用arr.a and arr.b作为数组成员访问字段。

numpy.recarray.ravel()函数返回返回连续的扁平记录数组，即具有所有输入数组元素且类型相同的一维数组。

Syntax : numpy.recarray.ravel([order])

Parameters:

order : [‘C’, ’F’, ‘A’, ‘K’, optional]

‘C’ means to index the elements in row-major, C-style order, with the last axis index changing fastest, back to the first axis index changing slowest.
‘F’ means to index the elements in column-major, Fortran-style order, with the first index changing fastest, and the last index changing slowest.
‘A’ means to read the elements in Fortran-like index order if a is Fortran contiguous in memory, C-like order otherwise.
‘K’ means to read the elements in the order they occur in memory, except for reversing the data when strides are negative.

By default, ‘C’ index order is used.

Return : [array_like] Flattened array having same type as the Input array and and order as per choice.

编程需要懂一点英语

代码#1：

# Python program explaining
# numpy.recarray.ravel() 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.ravel methods
# to float record array 
out_arr = rec_arr.a.ravel()
print ("Output flattenrd float array : ", out_arr) 
  
# applying recarray.ravel methods
# to int record array 
out_arr = rec_arr.b.ravel()
print ("Output flattenrd int 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 flattenrd float array :  [  5.   3.   6.   9.   5. -12.]
Output flattenrd int array :  [ 2 -4  9  1  4 -7]

代码#2：

我们将numpy.recarray.ravel()应用于整个记录数组。

# Python program explaining
# numpy.recarray.ravel() 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.ravel methods to  record array
out_arr = rec_arr.ravel()
  
print ("Output array : ", out_arr)

输出：

Input array :  [[( 5.,  2) ( 3.,  4) ( 6., -7)]
 [( 9.,  1) ( 6.,  4) (-2., -7)]]
Output array :  [( 5.,  2) ( 3.,  4) ( 6., -7) ( 9.,  1) ( 6.,  4) (-2., -7)]