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Wrong way to index: Index exceeds matrix dimensions

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I'm trying to use indices to expand a vector but I keep getting an error message and I don't understand why. In particular, what I'm trying to do works in an example such as
x=[1 2 3]';
y=[.1 .5 .3]';
z=[1 1 2 2 3];
Here I have two vectors, x and z that have the same values for the indices. I want to expand the vector y to have the same dimensions as z but the values of z must be repeated according to how the index is repeated.
Now, in my application this is not working. I have two vectors X and Z, X of dimensions 2270x1 and Z of dimensions 446723x1 that contains the same indices as X but a lot of times (and each number is repeated a different number of times). To check that the indices are the same I used isequal(unique(X),unique(Z)) and the output was 1.
Finally, I have a vector Y of dimensions 2270x1 that plays the role of y in the example above. When doing YZ=Y(Z) I get ??? Index exceeds matrix dimensions.
Any ideas what is going on?

Accepted Answer

ChristianW on 20 Mar 2013
max(Z) is greater then 2270?
Hideto Koizumi
Hideto Koizumi on 28 Aug 2018
Edited: Hideto Koizumi on 28 Aug 2018
I think this method could cut off the largest element of z, if z is something like z = [1 1 2 4] and y=[.1 .5 .3 .7]';

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More Answers (2)

Azzi Abdelmalek
Azzi Abdelmalek on 20 Mar 2013
Edited: Azzi Abdelmalek on 20 Mar 2013
Check this
What did you get?

Fernando on 20 Mar 2013
Thanks. Yes, the max of Z is greater than the number of elements in Y, which generates the message. Is there any way to overcome this? Following on the example, if this was
x=[1 2 5]';
y=[.1 .5 .3]';
z=[1 1 2 2 5];
I get the message because max(z)> size(y). How can I get yz to be yz=[.1 .1 .5 .5 .3]';?


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