replace elements in an Array with other elements
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i have the folwing situation:
i have an array:
A=[1 2 3 4 4 4 5 8 7 4 6 4]
i want to find the element equal to the value 4.
I do this:
i want now to replace the element with this index with the previous value. it means i want to get:
A_new=[1 2 3 3 3 3 5 8 7 7 6 6].
i did it with a loop. is there any method without loop?
Guillaume on 20 Jul 2015
While it may be possible to do it without a loop, with a combination of diff, find and possibly cumsum it's going to be a lot more obscure than a simple loop and probably not any more efficient.
The simplest loop would be:
for idx = find(A == 4)
A(idx) = A(idx-1);
which also works for consecutive elements to replace.
More Answers (3)
Walter Roberson on 20 Jul 2015
A_new = A;
A_new(index) = A(index-1);
This will fail if the very first thing was a 4, as there is no "previous" for the first element.