How to keep rows whose values follow a certain sequence?
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Lu Da Silva
el 3 de Feb. de 2022
Comentada: Stephen23
el 3 de Feb. de 2022
I have a matrix composed of two columns A and B, I need to only keep the rows which contain the sequence 90-180-270:
A B A B
-------- ----------
90 1 90 1
180 9 180 9
270 2 270 2
90 0 -> 90 0
270 3 180 4
90 0 270 6
180 4
270 6
How can I implement this into a Matlab code?
5 comentarios
Stephen23
el 3 de Feb. de 2022
Editada: Stephen23
el 3 de Feb. de 2022
"It only includes three possible numbers: 180, 270 and 90. (I wrote 1 2 3 for simplicity reasons)."
It is more complex and slower. Because solutions that work with 1-2-3 might not work with other values. But because you gave us incorrect information we all spend our time developing solutions that might not suit your needs at all.
You should tell us the exact values and the exact order.
Respuesta aceptada
Stephen23
el 3 de Feb. de 2022
Editada: Stephen23
el 3 de Feb. de 2022
Here is an old MATLAB trick that you can use, which still works today:
Where M is your matrix and S is the desired sequence:
S = [90,180,270]; % the required sequence
M = [90,1;180,9;270,2;90,0;270,3;90,0;180,4;270,6]
X = strfind(M(:,1).',S);
Y = X-1+(1:numel(S)).';
Z = M(Y,:)
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Más respuestas (1)
David Hill
el 3 de Feb. de 2022
s=strfind(num2str(yourMatrix(:,1))','123');
newMatrix=[];
for k=1:length(s)
newMatrix=[newMatrix;yourMatrix(s(k):s(k)+2,:)];
end
2 comentarios
David Hill
el 3 de Feb. de 2022
This should work.
r=yourMatrix(:,1);
r(r==90)=1;r(r==180)=2;r(r==270)=3;%change based on sequence desired
f=strfind(num2str(r)','123');
newMatrix=[];
for k=1:length(f)
newMatrix=[newMatrix;yourMatrix(f(k):f(k)+2,:)];
end
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