Python Numpy recarray.max()用法及代碼示例

在numpy中，數組可能具有包含字段的數據類型，類似於電子表格中的列。一個例子是[(a, int), (b, float)]，其中數組中的每個條目都是一對(int，float)。通常，這些屬性是使用字典查找(例如，arr['a'] and arr['b']。記錄數組允許使用以下方式將字段作為數組的成員進行訪問arr.a and arr.b。

numpy.recarray.max()函數返回記錄數組的最大值或沿軸的最大值。

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

參數：
axis :[無，整數或整數元組，可選]沿其運行的一個或多個軸。默認情況下，使用拚合的輸入。
out :[ndarray，可選]將結果存儲到的位置。
->如果提供，則必須具有廣播輸入的形狀。
->如果未提供或沒有，則返回新分配的數組。
keepdims :[布爾，可選]如果將其設置為True，則縮小的軸將保留為尺寸為1的尺寸。使用此選項，結果將針對輸入數組正確廣播。

Return :[ndarray或標量]記錄數組的最大值。如果axis為None，則結果為標量值。如果給定axis，則結果是尺寸為arr.ndim-1的數組。

代碼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)

輸出：

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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注：本文由純淨天空篩選整理自jana_sayantan大神的英文原創作品 Numpy recarray.max() function | Python。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。