selection of certain data from matrix

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Paul Rogers
Paul Rogers 2020-1-14
回答： Paul Rogers 2020-1-14
Hi, my problem is that I have 3 matrix:
FlowMeasurements, psic_pos_cheb and psic_neg_cheb.
I need a matrix done this way with:
- all the columns of the psic_neg_cheb where FlowMeasurements is negative
- all the columns of the psic_pos_cheb where FlowMeasurements is positive.
For example, in this case it would be a matrix whith the 1-6 colums of psic_neg_cheb,
and after the 7-20 colums of psic_pos_cheb.
The matrixes are in attached

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采纳的回答

Paul Rogers
Paul Rogers 2020-1-14
I finally did this way:
for i=1:length(FlowMeasurements)
if FlowMeasurements(i) < 0
CompressorMapMatrix(:,i) = psic_neg_cheb (:,i);
else
CompressorMapMatrix(:,i) = psic_pos_cheb (:,i);
end
end

更多回答（1 个）

Walter Roberson
Walter Roberson 2020-1-14
mask_pos = FlowMeasurements > 0;
mask_neg = FlowMeasurements < 0;
pos_part = psic_neg_cheb(:,mask_pos);
neg_part = psic_neg_cheb(:,mask_neg);
I would often tend to use ~mask_pos instead of constructing an entirely new mask, but ~mask_pos would include <= 0 not just < 0 and that is perhaps not acceptable.
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显示 1更早的评论
Paul Rogers
Paul Rogers 2020-1-14
编辑：Paul Rogers 2020-1-14
I see, it did't put rows and columns as it should, but it's anyway different values.
Paul Rogers
Paul Rogers 2020-1-14
the proble is that it takes the first 6 columns of
psic_neg_cheb
which is right, and also the last 14th columns of
psic_neg_cheb
instead of
psic_pos_cheb

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