# Select values in the matrix based on the condition

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Turbulence Analysis on 29 Jun 2022
Commented: Steven Lord on 29 Jun 2022
Hi,
I have two matrix A and B of 94349 x 1.
Here the values in the matrix A are range from 0 to 1. First, I have to identify row numbers in the matrix A that got values only in the range of 0.05 to 0.06. Then I have to read values from matrix B that pertains to only the preselected rows from step 1.

NIVEDITA MAJEE on 29 Jun 2022
Edited: NIVEDITA MAJEE on 29 Jun 2022
Hi,
You could do the following:
filtered_idx = find((A>=0.05 & A<=0.06)) %this will store the indexes from the matrix A which have values between 0.05 and 0.06
filtered_B = B(filtered_idx) %this will store the values corresponding to the indexes stored in filtered_idx
Hope this helps!
Steven Lord on 29 Jun 2022
You don't care where the items in the desired range are located, all you care is that you can select them. So you don't need find.
x = 1:10;
logicalMask = (4 <= x) & (x <= 7)
0 0 0 1 1 1 1 0 0 0
linearIndices = 1×4
4 5 6 7
You can use either the logical mask or the linear indices to obtain the values from x. But you can see that calling find is a second step beyond generating the logical mask, so if you don't actually need the linear indices why compute them?
ans = 1×4
4 5 6 7
x(linearIndices)
ans = 1×4
4 5 6 7

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