Effacer les filtres
Effacer les filtres

Strange results from unique

2 vues (au cours des 30 derniers jours)
David Winthrop
David Winthrop le 27 Mai 2021
I recently encountered a strange result that defies explanation. I took a screenshot. How can this be?
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the cyclist
the cyclist le 27 Mai 2021
It's always better to upload the data and code, rather than an image (which we cannot work with).
Yes, someone might be able to eyeball what is going on, but usually not.

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Walter Roberson
Walter Roberson le 27 Mai 2021
XLv{1} is a vector of 702 elements, YLv{1} is a vector of 702 elements. When you combine them you get 702 unique rows. But that does not imply that there are no duplicates amongst Xlv{1] or YLv{1} .
1 3
1 4
2 3
2 4
4 unique rows, right?
Now let XLvs be [1 2] and YLvs be [3 4]. ismember([1 1 2 2], [1 2]) would be [true true true true], ismember([3 4 3 4], [3 4]) would be [true true true true]. & the two of them to get [true true true true], which has a sum of 4... even though there are only 2 unique values in each of XLvs and YLvs.
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David Winthrop
David Winthrop le 27 Mai 2021
Modifié(e) : David Winthrop le 27 Mai 2021
Ah, I see that what I really wanted, since these are coordinate sets, is:
ismember([Xlv{1},Ylv{1}],[XLvs,YLvs],'rows')
This gives the expected result of length 85.
Thanks! I did not know ismember could match rows that way.

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