Finding any row in an array and replacing with certain new values

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inci
inci 2012-3-27
Hi,
In an array with certain repeated (or unrepeated) row values, I'd like to replace them with new values. i.e.:
a=[1 2 3; 4 5 6; 7 8 9; 1 2 3];
replace [1 2 3]s with [10 11 12]s:
new_a=[10 11 12; 4 5 6; 7 8 9; 10 11 12];
I am working with much bigger arrays and I don't know apriori how many times the row repeates itself.
So currently I am using:
a=[1 2 3; 4 5 6; 7 8 9; 1 2 3];
b=[1 2 3];
k=[10 11 12];
A=find(ismember(a,b,'rows')==1);
[c d] = size(A);
if c > 0
for i = 1:c
a(A(i),:)=k
end
end
But I need to do this operation for dozens of times (and dozens of rows) in a loop where the new values are obtained by "ginput" which makes it very ineffective.
I would so much appreciate any better suggestions.
Many thans,
inci

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回答（2 个）

Thomas
Thomas 2012-3-27
Will this help
a=[1 2 3; 4 5 6; 7 8 9; 1 2 3];
for i=1:length(a)
if a(i,:)==[1 2 3]
a(i,:)=[10 11 12]
end
end
for multiple substitutions you can add more if..else's.. Though this might not be the most elegant solution..
inci
inci 2012-3-27
It is much less clumsier than my solution for sure! Many thanks...

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