Shuffle two different lists of numbers in the same way

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Kavorka
Kavorka 2016-2-13
评论： Guillaume 2016-2-13
I want to shuffle two vectors, both with n elements, so that they are shuffled in the same way, i.e. the corresponding elements in each are moved to the same spot. I have tried doing this by using randperm like this:
ix = randperm(n);
ShuffledVector1 = Vector1(ix);
ShuffledVector2 = Vector2(ix);
But the shuffling is not done in the same way, I know because when I run it for Vector1=Vector2, ShuffledVector1 doesn't end up equaling ShuffledVector2. Any advice?
  2 个评论
Guillaume
Guillaume 2016-2-13
You're doing something wrong in your testing. If Vector1 == Vector2, then ShuffledVector1 == ShuffledVector2, always (with finite elements).
Jan
Jan 2016-2-13
编辑：Jan 2016-2-13
@Kavorka: Your assumption must be wrong:
If Vector1=Vector2, ShuffledVector1 doesn't end up
equaling ShuffledVector2.
How do you check this? Perhaps some elements are NaN, which reply FALSE for a comparison NaN==NaN ?

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回答（1 个）

Star Strider
Star Strider 2016-2-13
Maybe I’m missing something, but if ‘Vector1’ and ‘Vector2’ are different, ‘ShuffledVector1’ and ‘ShuffledVector2’ would be different as well.
Example 1:
Vector1 = randi(9, 1, 10);
Vector2 = randi(9, 1, 10);
ix = randperm(10);
ShuffeledVector1 = Vector1(ix);
ShuffeledVector2 = Vector2(ix);
Q1 = Vector1 == Vector2; % Not Equal
Q2 = ShuffeledVector1 == ShuffeledVector2; % Not Equal
Example 2:
Vector1 = randi(9, 1, 10);
Vector2 = Vector1;
ix = randperm(10);
ShuffeledVector1 = Vector1(ix);
ShuffeledVector2 = Vector2(ix);
Q1 = Vector1 == Vector2; % Equal
Q2 = ShuffeledVector1 == ShuffeledVector2; % Equal
  2 个评论
Kavorka
Kavorka 2016-2-13
I'm not saying the vectors aren't different, I want their order to be the same. It doesn't matter what the elements are, but if you assigned each element a number based on their order 1,2,3,4 then after the shuffle both vectors will have the same order 4,2,3,1 or whatever. If example 2 is true, then the shuffled order is the same and I must be doing something wrong after this operation. I will look again
Guillaume
Guillaume 2016-2-13
Yes, you're doing something wrong. Example 2 is true.
If you can't figure out where the problem is. Post the code you're using to test here.

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