Most Efficient Method To Find Maximum Element And List Of Maximum Elements From A 2-d Array?

Suppose I have a list arr=[[1,2,3],[4,5,6],[7,8,9]] here maximum element is 9 and maximum elements from 1 d list is [3,6,9].

Solution 1:

Flatten the array with a nested comprehension for the max of all elements:

>>>max(x for row in arr for x in row)
9

Use a list comprehension for the max of each row:

>>>[max(row) for row in arr]
[3, 6, 9]

Note: The list comp is slightly faster than using map(max, arr). Consider using numpy if you want better performance than pure Python loops.

Solution 2:

If using numpy

>>>import numpy as np

>>>array=np.random.rand(3,3)
>>>print(array)
>>>print(array.max(axis=1))

>>>[[ 0.76562624  0.45225107  0.74276688]
     [ 0.84390255  0.03384166  0.40036534]
     [ 0.00371805  0.47996941  0.15593055]]

>>>[ 0.765626240.843902550.47996941]

Alternatively using map and max

>>>arr=[[1,2,3],[4,5,6],[7,8,9]]
>>>print(list(map(max,arr)))

>>>[3,6,9]

To print maximum element

>>>print(max(map(max,arr)))

>>>9

Using numpy

>>>print(array.max())

Solution 3:

>>>arr=[[1,2,3],[4,5,6],[7,8,9]] >>>max_row = map(max, arr)>>>list(max_row)
[3, 6, 9]
>>>maxmax = max(max_row)>>>maxmax
9
>>>_