Numpy recarray.mean()函数| Python
原文:https://www . geeksforgeeks . org/numpy-recarray-mean-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']。使用arr.a and arr.b，记录数组允许字段作为数组的成员被访问。
numpy.recarray.mean() 函数返回给定轴上数组元素的平均值。
语法:
numpy.recarray.mean(axis=None, dtype=None, out=None, keepdims=False)参数: 轴:【无或 int 或 int 元组，可选】要沿其操作的一个或多个轴。默认情况下，使用展平输入。 数据类型:【数据类型，可选】计算平均值时我们想要的类型。 out:【n 数组，可选】存储结果的位置。 - >如果提供，它必须具有输入广播到的形状。 - >如果未提供或无，则返回新分配的阵列。 保持尺寸:【布尔，可选】如果设置为真，则缩小的轴作为尺寸为 1 的尺寸留在结果中。
返回:【n 数组或标量】数组(如果轴为无，则为标量值)或具有沿指定轴的平均值的数组的算术平均值。
代码#1 :
# Python program explaining
# numpy.recarray.mean() 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, 6), (6.0, 10)],
[(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.mean methods
# to float record array along default axis
# i, e along flattened array
out_arr1 = rec_arr.a.mean()
# Mean of the flattened array
print("\nMean of float record array, axis = None : ", out_arr1)
# applying recarray.mean methods
# to float record array along axis 0
# i, e along vertical
out_arr2 = rec_arr.a.mean(axis = 0)
# Mean along 0 axis
print("\nMean of float record array, axis = 0 : ", out_arr2)
# applying recarray.mean methods
# to float record array along axis 1
# i, e along horizontal
out_arr3 = rec_arr.a.mean(axis = 1)
# Mean along 0 axis
print("\nMean of float record array, axis = 1 : ", out_arr3)
# applying recarray.mean methods
# to int record array along default axis
# i, e along flattened array
out_arr4 = rec_arr.b.mean(dtype ='int')
# Mean of the flattened array
print("\nMean of int record array, axis = None : ", out_arr4)
# applying recarray.mean methods
# to int record array along axis 0
# i, e along vertical
out_arr5 = rec_arr.b.mean(axis = 0)
# Mean along 0 axis
print("\nMean of int record array, axis = 0 : ", out_arr5)
# applying recarray.mean methods
# to int record array along axis 1
# i, e along horizontal
out_arr6 = rec_arr.b.mean(axis = 1)
# Mean along 0 axis
print("\nMean of int record array, axis = 1 : ", out_arr6)
Output:
Input array : [[( 5., 2) ( 3., 6) ( 6., 10)]
[( 9., 1) ( 5., 4) (-12., 7)]]
Record array of float: [[ 5\. 3\. 6.]
[ 9\. 5\. -12.]]
Record array of int: [[ 2 6 10]
[ 1 4 7]]
Mean of float record array, axis = None : 2.6666666666666665
Mean of float record array, axis = 0 : [ 7\. 4\. -3.]
Mean of float record array, axis = 1 : [4.66666667 0.66666667]
Mean of int record array, axis = None : 5
Mean of int record array, axis = 0 : [1.5 5\. 8.5]
Mean of int record array, axis = 1 : [6\. 4.]
