Python Numpy recarray.mean()用法及代码示例

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，这些属性是使用字典查找(例如，arr['a'] and arr['b']。记录数组允许使用以下方式将字段作为数组的成员进行访问arr.a and arr.b。

numpy.recarray.mean()函数返回沿给定轴的数组元素的平均值。

用法： numpy.recarray.mean(axis=None, dtype=None, out=None, keepdims=False)

参数：
axis :[无，整数或整数元组，可选]沿其运行的一个或多个轴。默认情况下，使用拼合的输入。
dtype :[数据类型，可选]计算均值时需要的类型。
out :[ndarray，可选]将结果存储到的位置。
->如果提供，则必须具有广播输入的形状。
->如果未提供或没有，则返回新分配的数组。
keepdims :[布尔，可选]如果将其设置为True，则缩小的轴将保留为尺寸为1的尺寸。

Return :[ndarray或scalar]数组的算术平均值(如果轴不存在，则为标量值)或具有沿指定轴的平均值的数组。

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)

输出：

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.]

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注：本文由纯净天空筛选整理自jana_sayantan大神的英文原创作品 Numpy recarray.mean() function | Python。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。