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Numpy recarray.max()函数| Python

原文:https://www . geeksforgeeks . org/numpy-recarray-max-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.max() 函数返回记录数组的最大值或沿一个轴的最大值。

语法: numpy.recarray.max(axis=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。 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。使用此选项,结果将根据输入数组正确广播。

返回:【数组或标量】记录数组的最大值。如果轴为“无”,则结果为标量值。如果给定轴,结果是一个 arr . ndim–1 维的数组。

代码#1 :

# Python program explaining
# numpy.recarray.max() 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, 8)],
                     [(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.max methods
# to float record array along default axis 
# i, e along flattened array
out_arr1 = rec_arr.a.max()
# Maximum of the flattened array 
print("\nMax of float record array, axis = None : ", out_arr1) 

# applying recarray.max methods
# to float record array along axis 0
# i, e along vertical
out_arr2 = rec_arr.a.max(axis = 0)
# Maximum along 0 axis
print("\nMax of float record array, axis = 0 : ", out_arr2)

# applying recarray.max methods
# to float record array along axis 1
# i, e along horizontal
out_arr3 = rec_arr.a.max(axis = 1)
# Maximum along 0 axis
print("\nMax of float record array, axis = 1 : ", out_arr3)

# applying recarray.max methods
# to int record array along default axis 
# i, e along flattened array
out_arr4 = rec_arr.b.max()
# Maximum of the flattened array 
print("\nMax of int record array, axis = None : ", out_arr4) 

# applying recarray.max methods
# to int record array along axis 0
# i, e along vertical
out_arr5 = rec_arr.b.max(axis = 0)
# Maximum along 0 axis
print("\nMax of int record array, axis = 0 : ", out_arr5)

# applying recarray.max methods
# to int record array along axis 1
# i, e along horizontal
out_arr6 = rec_arr.b.max(axis = 1)
# Maximum along 0 axis
print("\nMax of int record array, axis = 1 : ", out_arr6)

Output:

Input array :  [[(  5.,  2) (  3., -4) (  6.,  8)]
 [(  9.,  1) (  5.,  4) (-12., -7)]]
Record array of float:  [[  5\.   3\.   6.]
 [  9\.   5\. -12.]]
Record array of int:  [[ 2 -4  8]
 [ 1  4 -7]]

Max of float record array, axis = None :  9.0

Max of float record array, axis = 0 :  [9\. 5\. 6.]

Max of float record array, axis = 1 :  [6\. 9.]

Max of int record array, axis = None :  8

Max of int record array, axis = 0 :  [2 4 8]

Max of int record array, axis = 1 :  [8 4]



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