Can the diff function go the opposite direction?

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Teddy Fisher 2019-12-18

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评论： Steven Lord 2019-12-19

Hello,

As I understand diff it goes either left to right along rows or up to down a column. Is there a way to make diff do the same thing it currently does but go right to left or down to up?

Thanks,

Teddy

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Jeremy 2019-12-18

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sure, flip your matrix with

fliplr

flipud

and then run

diff

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Jeremy 2019-12-19

Wouldn't you fliplr the original array, call diff on it, and then flip the resulting array again to get what you want?

Steven Lord 2019-12-19

在 MATLAB Online 中打开

So you want to detect when the abs-olute diff-erence between adjacent elements is exactly 1?

If you know that your data only contains 0 and 1 (or false and true) it's even easier than using abs and diff.

x = randi([0 1], 1, 10)
d = [x(1:end-1) ~= x(2:end), 0]
[x; d]

Each element of d is true when the corresponding element of x differs from the next element in x. I set the last element of d to false because it doesn't make sense to ask if the last element is different from the nonexistent next-after-the-last element.

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