Assigning values from one array to another if certain specifications are met.
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Tadas Grauzinis
am 13 Apr. 2020
Bearbeitet: Adam Danz
am 13 Apr. 2020
I have a few arrays
A= 0 1 2 3 6 8 9 10
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
B= 20 5 15 10
9 8 2 1
C= 10 15
9 3
Bassically the first row of A contains special points from a line that goes from 0 to 10 and the other two rows are where the values from B( to second row) and C( to third row) should go. Second rows of B and C are corresponding points from the first row of A.
For example. Since B(2,1)=A(1,7) then B(1,1) should go to A(2,7) like this:
A= 0 1 2 3 6 8 9 10
0 0 0 0 0 0 20 0
0 0 0 0 0 0 0 0
The final result should look like this:
A= 0 1 2 3 6 8 9 10
0 10 15 0 0 5 20 0
0 0 0 15 0 0 10 0
I am very much still a beginner in Matlab. I am writing a script that would calculate shear forces and bending moments of a cantilever beam so any advice and/or suggestions would be greatly appreciated.
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Akzeptierte Antwort
Adam Danz
am 13 Apr. 2020
Inputs:
A= [ 0 1 2 3 6 8 9 10
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0];
B= [ 20 5 15 10
9 8 2 1];
C= [10 15
9 3];
Solution:
[isMatch, col] = ismember(B(2,:), A(1,:));
A(2,col(isMatch)) = B(1,isMatch);
[isMatch, col] = ismember(C(2,:), A(1,:));
A(3,col(isMatch)) = C(1,isMatch);
Result:
>> A
A =
0 1 2 3 6 8 9 10
0 10 15 0 0 5 20 0
0 0 0 15 0 0 10 0
4 Kommentare
Adam Danz
am 13 Apr. 2020
Bearbeitet: Adam Danz
am 13 Apr. 2020
Good question. Suppose matrix B was
B= [ 20 5 15 10
9 8 200 1];
There is no match for 200 so col would return 0 for that match. A(2,col) would then return an error since indices must be positive, non-zero integers. So, col(isMatch) makes sure you're only selecting col values that correspond to matches. It's a safety net.
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Kevin Hellemans
am 13 Apr. 2020
Bearbeitet: Adam Danz
am 13 Apr. 2020
Hi,
I think this should do the trick:
A= [0 1 2 3 6 8 9 10; ...
0 0 0 0 0 0 0 0; ...
0 0 0 0 0 0 0 0];
B = [20 5 15 10; 9 8 2 1];
C=[10 15; 9 3];
A(2,B(2,:)) = B(1,:);
A(3,C(2,:)) = C(1,:);
disp(A)
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