swap only 2 elements in an array
显示 更早的评论
I'm try to come up with a function that can randomly swap 2 elements (and only 2 at a time) from an array of 20 unique numbers.
Say a=randperm(20) a=[4 1 9 13 5 20 19 ....] would become anew=[19 1 9 13 5 20 4 ....]
采纳的回答
Star Strider
2015-10-13
This works:
a=[4 1 9 13 5 20 19]
a([1 7]) = a([7 1])
a =
4 1 9 13 5 20 19
a =
19 1 9 13 5 20 4
6 个评论
Erik Lee
2015-10-13
Star Strider
2015-10-13
This is how I would do it:
a=randperm(20)
idx = randi(20, 1, 2)
a(idx) = a(flip(idx))
This prints out everything so you can verify that it works.
Erik Lee
2015-10-13
Star Strider
2015-10-13
To keep the original vector, returning the switched one as ‘anew’, insert one additional assignment:
a=randperm(20)
anew = a
idx = randi(20, 1, 2)
anew(idx) = anew(flip(idx))
The new line simply duplicates ‘a’ as ‘anew’ and does the same operation on ‘anew’ as it originally did on ‘a’.
Erik Lee
2015-10-13
Star Strider
2015-10-13
My pleasure!
更多回答（2 个）
Guillaume
2015-10-13
a = randperm(20)
swapidx = randperm(numel(a), 2);
a(swapidx) = a(fliplr(swapidx))
Mohammed
2023-5-27
if the array is 2D ( two dimantion ) you can use this and get it how it work
a=[10 20
30 40 ]
%For swapping number in Array 2D
%[10 is a 1] & [30 is 2] & [20 is a 3] & 40 is a 4
a([2 3])=a([3 2])
OUTPUT:
a =
10 20
30 40
a =
10 30
20 40
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