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Numpy recarray.argmin()函数| Python

原文:https://www . geesforgeks . org/numpy-recarray-arg min-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.argmin() 函数返回特定轴上数组的最小元素的索引。

语法: numpy.recarray.argmin(axis=None, out=None)

参数: 轴:【int,可选】沿指定轴如 0 或 1 出:【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。

返回:【整数数组】数组中的索引,其形状与数组相同。沿轴的尺寸被移除的形状。

代码#1 :

# Python program explaining
# numpy.recarray.argmin() 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.argmin methods to
# float record array along axis 1
out_arr = geek.recarray.argmin(rec_arr.a, axis = 1)
print ("Output array along axis 1: ", out_arr) 

# applying recarray.argmin methods to
# int record array along axis 0
out_arr = geek.recarray.argmin(rec_arr.b, axis = 0)
print ("Output array along axis 0: ", out_arr) 

Output:

Input array :  [[(5.0, 2) (3.0, 4) (6.0, 9)]
 [(9.0, 1) (5.0, 4) (-12.0, -7)]]
Record array of float:  [[  5\.   3\.   6.]
 [  9\.   5\. -12.]]
Record array of int:  [[ 2  4  9]
 [ 1  4 -7]]
Output array along axis 1:  [1 2]
Output array along axis 0:  [1 0 1]

代码#2 :

如果我们将numpy.recarray.argmin()应用于整个记录数组,那么它将给出Type error

# Python program explaining
# numpy.recarray.argmin() 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.argmin methods to  record array
out_arr = geek.recarray.argmin(rec_arr)

Output:

TypeError:无法根据规则“safe”将数组数据从 dtype(((numpy . record,[('a ',' < f8 '),(' b ',' < i8 ')))强制转换为 dtype('V16 ')



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