Python numpy.argmax()
Python numpy.argmax()函数返回数组中最大元素在特定axis上的下标。
语法 :
numpy.argmax(array, axis = None, out = None)
参数 :
array : 输入数组来工作。
axis : [int, optional]沿着一个指定的轴,如0或1。
out : [array optional]提供了一个插入输出到out数组的功能,它应该是适当的形状和dtype。
返回 :
与array.shape相同形状的数组,去掉了沿轴线的维度,是数组的索引。
代码1 :
# Python Program illustrating
# working of argmax()
import numpy as geek
# Working on 2D array
array = geek.arange(12).reshape(3, 4)
print("INPUT ARRAY : \n", array)
# No axis mentioned, so works on entire array
print("\nMax element : ", geek.argmax(array))
# returning Indices of the max element
# as per the indices
print("\nIndices of Max element : ", geek.argmax(array, axis=0))
print("\nIndices of Max element : ", geek.argmax(array, axis=1))
输出 :
INPUT ARRAY :
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]]
Max element : 11
Indices of Max element : [2 2 2 2]
Indices of Max element : [3 3 3]
代码 2 :
# Python Program illustrating
# working of argmax()
import numpy as geek
# Working on 2D array
array = geek.random.randint(16, size=(4, 4))
print("INPUT ARRAY : \n", array)
# No axis mentioned, so works on entire array
print("\nMax element : ", geek.argmax(array))
# returning Indices of the max element
# as per the indices
'''
[[ 0 3 8 13]
[12 11 2 11]
[ 5 13 8 3]
[12 15 3 4]]
^ ^ ^ ^
12 15 8 13 - element
1 3 0 0 - indices
'''
print("\nIndices of Max element : ", geek.argmax(array, axis = 0))
'''
ELEMENT INDEX
->[[ 0 3 8 13] 13 3
->[12 11 2 11] 12 0
->[ 5 13 8 3] 13 1
->[12 15 3 4]] 15 1
'''
print("\nIndices of Max element : ", geek.argmax(array, axis = 1))
输出 :
INPUT ARRAY :
[[ 0 3 8 13]
[12 11 2 11]
[ 5 13 8 3]
[12 15 3 4]]
Max element : 15
Indices of Max element : [1 3 0 0]
Indices of Max element : [3 0 1 1]
代码 3 :
# Python Program illustrating
# working of argmax()
import numpy as geek
# Working on 2D array
array = geek.arange(10).reshape(2, 5)
print("array : \n", array)
array[0][1] = 6
print("\narray : \n", array)
# Returns max element
print("\narray : ", geek.argmax(array))
# First occurrence of an max element is given
print("\nMAX ELEMENT INDICES : ", geek.argmax(array, axis = 0))
输出 :
array :
[[0 1 2 3 4]
[5 6 7 8 9]]
array :
[[0 6 2 3 4]
[5 6 7 8 9]]
array : 9
MAX ELEMENT INDICES : [1 0 1 1 1]