Numpy recarray.swapaxes()函数| Python
原文:https://www . geeksforgeeks . org/numpy-recarray-swapaxes-function-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)]，数组中的每个条目都是一对(int，float)。通常，这些属性是使用字典查找来访问的，例如arr['a'] and arr['b']。
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.swapaxes() 函数返回 axis1 和 axis2 互换的数组视图。
语法:
numpy.recarray.swapaxes(axis1, axis2)参数: 轴 1:【int】第一轴。 轴 2:【int】第二轴。
返回:【非数组】结果数组。
代码#1 :
# Python program explaining
# numpy.recarray.swapaxes() 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.swapaxes methods
# to float record array taking axis1 = 0 and axis2 = 1
out_arr = rec_arr.a.swapaxes(0, 1)
print ("Output float array : ", out_arr)
# applying recarray.swapaxes methods
# to int record array taking axis1 = 1 and axis2 = 0
out_arr = rec_arr.b.swapaxes(1, 0)
print ("Output int 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 float array : [[ 5\. 9.]
[ 3\. 5.]
[ 6\. -12.]]
Output int array : [[ 2 1]
[-4 4]
[ 9 -7]]
代码#2 :
我们将numpy.recarray.swapaxes()应用于整个记录数组。
# Python program explaining
# numpy.recarray.swapaxes() 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.swapaxes methods to
# record array taking axis1 = 0 and axis2 = 1
out_arr = rec_arr.swapaxes(1, 0)
print ("Output record array : ", out_arr)
Output:
Input array : [[( 5., 2) ( 3., 4) ( 6., -7)]
[( 9., 1) ( 6., 4) (-2., -7)]]
Output record array : [[( 5., 2) ( 9., 1)]
[( 3., 4) ( 6., 4)]
[( 6., -7) (-2., -7)]]
