Randomizing the rows of a matrix and reversing

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Mohsin Shah 2017-8-1

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评论： Mohsin Shah 2017-8-2

Hello, I have a 988 x 3 matrix (say the vertices of 3D object) and I want to randomize the rows of this matrix and then do the reverse process to get the original matrix. I am using the following code to do the job:

The above code doesn't produce the original matrix. Can someone highlight my mistake and give me a solution?

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José-Luis 2017-8-1

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编辑：José-Luis 2017-8-1

If you want to return to the original matrix, you need to keep it. There is no way to undo a random permutation, unless your data was ordered/structured in some way (was it?). If it was ordered, how so? The key word is random.

Just to be psychotic about it. randperm() is not random but pseudo-random. If you knew the state of the random number generator, it could be possible to go back to the original. I am guessing this is not what you had in mind.

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José-Luis 2017-8-1

编辑：José-Luis 2017-8-1

Then you need to pass the two indexes or the state of your random number generator to recreate them.

That being said, this does not feel like the best way of hiding data, but what do I know :)

Mohsin Shah 2017-8-2

Thank you so much. This is only to permute the locations for achieving more security. The hiding itself is a complex algorithm and has nothing to do with permutation.

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