Simulink vector index assignment / re-ordering using Selector block

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Bill Tubbs
Bill Tubbs 2022-3-4
评论： Bill Tubbs 2022-3-5
I'm trying to merge two vector signals into one vector according to two sets of indices.
For example:
u_pos = [2 3 4];
du_pos = [1 5 6 7];
These indicate the 'indices' of the combined signal where each element of each of the two input vectors is intended to go.
One way to do this might be to use a selector block like this:
This achieves the result, but to get the the correct assignment of the elements as above, I need to provide the following index vector to the selector block:
[4 1 2 3 5 6 7]
These are the indices of the input vector, not the output vector—which I have in my two index vectors above.
Obviously I could use two assignment blocks instead, but it's a more complicated solution than the selector block and also requires a zeros vector of the correct size:
Also, I like that the selector block shows the connections graphically. This is important to me.
Is there an easy way I can use a selector block? Maybe by converting my index vectors perhaps.
  1 个评论
Bill Tubbs
Bill Tubbs 2022-3-4
Here is one way to convert the 'output index' vector to an 'input index':
>> [~,idx] = ismember(1:length([u_pos du_pos]), [u_pos du_pos])
idx =
4 1 2 3 5 6 7
but I'm not sure I can put this in the Simulink selector dialog cell can I?

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采纳的回答

Paul
Paul 2022-3-4
Normally, you can put any Matlab expression in a block parameter dialog. So if u_pos and du_pos are defined in a workspace that the Selector block can access, you sould be able to put the "ismember( ..." expression in the dialog for the Index parameter.
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Paul
Paul 2022-3-5
I think the Assignment block is really what's expected to be used for this operation.
It can be done with a one Assignment block, with u and du muxed, the output of the mux feeding the Y0 and U input ports of the Assignment block, and its Index parameter being [u_pos du_pos]. So not more complicated than the Selector approach (IMO) and no need to define the constant zero vector. The only thing it doesn't do is graphically show the rearrangement on the block icon.

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